Shop All Protein Analysis Kits

Easy-Titer™ Mouse IgG Assay Kit (Thermo Scientific™)

The Thermo Scientific Easy-Titer Mouse IgG Assay Kit includes antibody-sensitized microspheres to measure the specific concentration of antibodies by an easy and rapid microagglutination technique using standard microplates and UV-Vis plate reader (spectrophotometer). This kit is specific for mouse IgG and, unlike total protein assays, can specifically measure the concentration of target antibody in samples (e.g., serum, plasma, culture supernatant) that contain other proteins. It is sensitive, requiring very small sample volumes. Antibody concentration is determined from the assay response (absorbance) by comparison to a standard curve prepared using dilutions of a known antibody sample (sold separately).

General features of Easy-Titer Antibody Assay Kits:

Antibody-based specificity—measure concentration of target antibody in a sample, not just total protein; no need to purify antibody to assess its concentration
Faster and easier than ELISA—three-component, homogenous assay; 10 minutes total incubation time
No special equipment needed—uses standard vortex mixer, pipetter, 96-well microplate, plate shaker and reader (measure absorbance at 340nm or 400nm)
Sensitive—assay range (standard curve) 8 to 500 ng/mL; use sample at 15 to 300 ng/mL for optimal results
Reproducible—coefficient of variation < 5%; error depends on dilution and pipetting technique
Antibody standards sold separately—see product list for suggested products; use any antibody standard with proper target identity and known concentration (greater than 10 µg/mL)
Kits for five popular targets—choose a kit specific for a particular species and class of immunoglobulin; no cross-reaction with other species and classes of the target antibody

Easy-Titer Assay Kits detect and measure specific target antibodies using agglutination of microspheres that are coated ("sensitized") with the specific anti-IgG or IgM polyclonal antibodies. In the appropriate aqueous buffer (supplied in kit), the monodispersed antibody-coated microspheres (> 1 µM diameter) have highest absorptivity (λ-max) to incident light having a wavelength (340nm) that is equal to approximately half their diameter. When sample is added, two or more microspheres bind to each antibody target via their coated specific polyclonal antibodies, and this agglutination into effectively larger apparent spheres results in proportional decrease in absorptivity (lower absorbance).

Typical microagglutination assays depend on a change in light-scattering and corresponding change in transmittance, to which absorbance is inversely related. Easy-Titer Assay Kits use a special dilution buffer whose refractive index eliminates the effect of light-scattering on the monodispersed microspheres for the measurement wavelength used. Because of this, the final 10- to 20-fold dilution of the sample for use in the assay must be done using the Dilution Buffer supplied in the kit.

Easy-Titer Antibody Assays are faster and easier than ELISA:
• Prepare standards (5 to 500 ng/mL) by diluting purified antibody in Kit Dilution Buffer.
• Prepare samples by diluting in Dilution Buffer to within assay range (8 to 500 ng/mL).
• Vortex vial of microsphere beads to create homogeneous suspension.
• Pipette 20 µL of bead suspension and 20 µL of each sample and standard into 96-well microplate wells.
• Incubate microplate for 5 minutes with vigorous mixing.
• Add 100 µL of Kit Blocking Reagent.
• Incubate microplate for 5 minutes with vigorous mixing.
• Measure absorbance on standard plate reader (340nm or 405nm).
• Plot standard curve and interpolate samples to determine concentration.

Related Products
Easy-Titer™ Rabbit IgG Assay Kit
Easy-Titer™ Human IgG (H+L) Assay Kit
Easy-Titer™ Human IgG (gamma chain) Assay Kit
Easy-Titer™ Human IgM Assay Kit

Pierce™ Rapid Gold BCA Protein Assay Kit (Thermo Scientific™)

The Thermo Scientific Pierce Rapid Gold BCA Protein Assay Kit is a two-component, high-precision, detergent-compatible assay optimized to measure (at 480 nm) total protein concentration compared to a protein standard curve of known concentrations. The Pierce Rapid Gold BCA Protein Assay uses the same copper-chelating technology as the well-known traditional Pierce BCA Protein Assay and provides comparable accuracy but with a 5 minute, room temperature incubation and measured at 480 nm. This improvement eliminates the need to wait or expose the samples to elevated temperatures for a fast time to results.

Features of the Rapid Gold BCA Protein Assay Kit:
• Colorimetric—estimate visually or measure with a standard spectrophotometer or plate reader (480 nm)
• Excellent uniformity—exhibits similar protein-to-protein variation as traditional BCA Protein Assay, and less protein-to-protein variation than dye-binding protein assay methods
• Compatible—unaffected by typical concentrations of most ionic and nonionic detergents
• Fast time to results—significant improvement over traditional BCA Assay with a 5 minute, room temperature reaction
• High linearity—linear working range for BSA equals 20 to 2000 µg/mL
• Optimal absorbance on standard spectrophotometers—reaction produces a color change to an intense orange-gold that results in a strong linear response at 480 nm

The traditional BCA Protein Assay is a widely used and accepted protein assay, trusted for its highly accurate protein concentration determination and compatibility with most sample types encountered in protein research. However, in order to develop the samples in this traditional protocol, one must either heat the reaction at 37°C for 30 minutes or allow room temperature development for 2 hours. The Rapid Gold BCA Protein Assay maintains the key characteristics of the traditional BCA assay but allows a fast time and room temperature incubation equal to dye-binding methods. The Rapid Gold BCA assay can be used to assess yields in whole cell lysates and affinity-column fractions, as well as to monitor protein contamination in industrial applications. Compared to most dye-binding methods and similar to the traditional BCA assay, the Rapid Gold BCA assay is affected much less by protein compositional differences, providing low protein-to-protein variation.

Applications:
• Studying protein:protein interactions
• Measuring column fractions after affinity chromatography
• Estimating percent recovery of membrane proteins from cell extracts
• High-throughput screening of fusion proteins

How the Rapid Gold BCA Protein Assay detects protein
The Rapid Gold BCA Protein Assay uses the same copper reduction method as the traditional BCA Protein Assay with a proprietary copper chelator. The Rapid Gold BCA assay combines the well-known reduction of Cu2+ to Cu1+ by protein in an alkaline medium with the highly sensitive and selective colorimetric detection of the cuprous cation (Cu1+) by the proprietary chelator. The first step is the chelation of copper with protein in an alkaline environment to form a light green complex. In this reaction, known as the biuret reaction, peptides containing three or more amino acid residues form a colored chelate complex with cupric ions in an alkaline environment containing sodium potassium tartrate.

In the second step of the color development reaction, the Rapid Gold BCA chelator reacts with the reduced (cuprous) cation that was formed in step one. The intense gold-colored reaction product results from the chelation of two molecules of BCA with one cuprous ion. The BCA/copper complex is water-soluble and exhibits a strong linear absorbance at 480 nm with increasing protein concentrations. The BCA reagent is approximately 100 times more sensitive (lower limit of detection) than the pale green color of the first reaction.

The reaction that leads to the color formation is strongly influenced by four amino acid residues (cysteine or cystine, tyrosine, and tryptophan) in the amino acid sequence of the protein. However, unlike the Coomassie dye-binding methods, the universal peptide backbone also contributes to color formation, helping to minimize variability caused by protein compositional differences.

Compatibility of the Rapid Gold BCA Protein Assay
Certain substances are known to interfere with the Rapid Gold BCA Protein Assay including those with reducing potential, chelating agents, and strong acids or bases. Because they are known to interfere with protein estimation at even minute concentrations, avoid the following substances as components of the sample buffer:
• Ascorbic acid
• EGTA
• Iron
• Impure sucrose
• Catecholamines
• Impure glycerol
• Lipids
• Tryptophan
• Creatinine
• Hydrogen peroxide
• Melibiose
• Tyrosine
• Cysteine
• Hydrazides
• Phenol Red
• Uric acid

Protein assays using a copper chelator are found to be highly advantageous in that most surfactants (even if present in the sample at concentrations up to 5%) are compatible with the assay. Thermo Fisher Scientific has performed extensive compatibility experiments on all of our protein assays, in particular for the traditional BCA Protein Assay. The new Rapid Gold BCA Protein Assay was determined to have similar compatibility of interfering substances as traditional BCA. Additional data and information can be found in the instructional booklet for each protein assay.

Easy-Titer™ Human IgG (H+L) Assay Kit (Thermo Scientific™)

The Thermo Scientific Easy-Titer Human IgG (H+L) Assay Kit includes antibody-sensitized microspheres to measure the specific concentration of antibodies by an easy and rapid microagglutination technique using standard microplates and UV-Vis plate reader (spectrophotometer). This kit is specific for human IgG and, unlike total protein assays, can specifically measure the concentration of target antibody in samples (e.g., serum, plasma, culture supernatant) that contain other proteins. It is sensitive, requiring very small sample volumes. Antibody concentration is determined from the assay response (absorbance) by comparison to a standard curve prepared using dilutions of a known antibody sample (sold separately).

General features of Easy-Titer Antibody Assay Kits:

Antibody-based specificity—measure concentration of target antibody in a sample, not just total protein; no need to purify antibody to assess its concentration
Faster and easier than ELISA—three-component, homogenous assay; 10 minutes total incubation time
No special equipment needed—uses standard vortex mixer, pipetter, 96-well microplate, plate shaker and reader (measure absorbance at 340nm or 400nm)
Sensitive—assay range (standard curve) 8 to 500 ng/mL; use sample at 15 to 300 ng/mL for optimal results
Reproducible—coefficient of variation < 5%; error depends on dilution and pipetting technique
Antibody standards sold separately—see product list for suggested products; use any antibody standard with proper target identity and known concentration (greater than 10 µg/mL)
Kits for five popular targets—choose a kit specific for a particular species and class of immunoglobulin; no cross-reaction with other species and classes of the target antibody

Easy-Titer Assay Kits detect and measure specific target antibodies using agglutination of microspheres that are coated ("sensitized") with the specific anti-IgG or IgM polyclonal antibodies. In the appropriate aqueous buffer (supplied in kit), the monodispersed antibody-coated microspheres (> 1 µM diameter) have highest absorptivity (λ-max) to incident light having a wavelength (340nm) that is equal to approximately half their diameter. When sample is added, two or more microspheres bind to each antibody target via their coated specific polyclonal antibodies, and this agglutination into effectively larger apparent spheres results in proportional decrease in absorptivity (lower absorbance).

Typical microagglutination assays depend on a change in light-scattering and corresponding change in transmittance, to which absorbance is inversely related. Easy-Titer Assay Kits use a special dilution buffer whose refractive index eliminates the effect of light-scattering on the monodispersed microspheres for the measurement wavelength used. Because of this, the final 10- to 20-fold dilution of the sample for use in the assay must be done using the Dilution Buffer supplied in the kit.

Easy-Titer Antibody Assays are faster and easier than ELISA:
• Prepare standards (5 to 500 ng/mL) by diluting purified antibody in Kit Dilution Buffer.
• Prepare samples by diluting in Dilution Buffer to within assay range (8 to 500 ng/mL).
• Vortex vial of microsphere beads to create homogeneous suspension.
• Pipette 20 µL of bead suspension and 20 µL of each sample and standard into 96-well microplate wells.
• Incubate microplate for 5 minutes with vigorous mixing.
• Add 100 µL of Kit Blocking Reagent.
• Incubate microplate for 5 minutes with vigorous mixing.
• Measure absorbance on standard plate reader (340nm or 405nm).
• Plot standard curve and interpolate samples to determine concentration.

Related Products
Easy-Titer™ Mouse IgG Assay Kit
Easy-Titer™ Rabbit IgG Assay Kit
Easy-Titer™ Human IgG (gamma chain) Assay Kit
Easy-Titer™ Human IgM Assay Kit

Pierce™ Glycoprotein Carbohydrate Estimation Kit (Thermo Scientific™)

The Thermo Scientific Pierce Glycoprotein Carbohydrate Estimation Kit enables the amount of protein glycosylation to be measured as the percent of total purified protein mass.

Features of the Glycoprotein Carbohydrate Estimation Kit:

Qualitative—easily identifies purified proteins as glycoproteins or samples as contaminated with sugars
Semi-quantitative—estimates the percent carbohydrate content (w/w) of purified glycoprotein by comparison to the included set of glycoprotein standards
Simple procedure—completed in less than 75 minutes; instructions include microplate and test tube protocols
Adaptable—standard curve format allows for the design of alternative tests for aldehydes and carbohydrate components

The Glycoprotein Carbohydrate Estimation Kit includes six purified glycoprotein standards and the required assay reagents to effectively estimate the amount of oxidizable glycosylation (percent carbohydrate by weight) of purified protein samples. Sugar groups in the glycoprotein sample are first oxidized with sodium meta-periodate to produce detectable aldehyde groups. Then the sample is reacted with the colorimetric Glycoprotein Detection Reagent. Absorbance at 550 nm of the resulting purple reaction product is measured with a spectrophotometer or plate reader. Finally, the carbohydrate content in the glycoprotein is calculated by comparison to results from the five glycoprotein standards that are included in the kit.

Applications
• Determine if a purified polyclonal antibody or other protein is glycosylated before attempting to perform carbohydrate-based conjugation or immobilization chemistries with hydrazide reagents
• Characterize and classify purified protein fractions from an affinity procedure
• Assess sugar and carbohydrate contamination in non-glycosylated protein samples

Related Products
Glycoprotein Standards Set for Pierce™ Glycoprotein Carbohydrate Estimation Kit

Pierce™ c-Myc-Tag Magnetic IP/Co-IP Kit (Thermo Scientific™)

The Thermo Scientific Pierce Magnetic c-Myc-Tag IP/Co-IP Kit contains specific immunoaffinity magnetic beads and reagents to perform immunoprecipitation assays of c-Myc fusion proteins or co-IP experiments using c-Myc-tagged bait proteins.

Unlike traditional IP procedures based on capture with Protein A/G beads, this kit uses magnetic beads containing pre-immobilized anti-c-Myc antibody. These Pierce Anti-c-Myc Magnetic Beads ensure specific binding of c-Myc tagged protein complexes from biological samples. Because the antibody is covalently attached to the beads, IP-targets are easily eluted and recovered without antibody contamination. The complete IP kit includes the magnetic beads, lysis/wash buffer, low-pH elution buffer, neutralization buffer, c-Myc-tag positive control lysate, and non-reducing sample buffer for SDS-PAGE. Protocols are provided for both manual and automated magnetic separation workflows. Sufficient components are provided to perform 40 IP or co-IP assays.

Features of the c-Myc-Tag Magnetic IP/Co-IP Kit:

Specific magnetic beads—covalently immobilized high-quality anti-c-Myc monoclonal antibody enables high yields of immunoprecipitation products
Low non-specific binding—stable, pre-blocked beads and specific antibody minimize off-target binding
Trouble-free elution—low-pH elution buffer ensures recovery of c-Myc-tagged protein interaction complexes without antibody leaching contamination
Convenient and fast—complete kit and easy-to-follow instructions provide optimized protocols to perform IP or Co-IP experiment in approximately 1 hour
Versatile—magnetic beads are compatible with manual and automated magnetic separation workflows (e.g., Thermo Scientific KingFisher Instruments)

The c-Myc peptide (EQKLISEEDL) derived from the C-terminus region of human c-Myc protein is one of several fusion protein tags used for recombinant protein expression. The Pierce c-Myc Magnetic IP/Co-IP Kit uses a specific, high-affinity immobilized antibody (clone 9E10) for rapid immunoprecipitation of c-Myc tagged fusion proteins from bacterial and mammalian cell lysates, as well as from lysates prepared with the Pierce Human in vitro Translation Kits. The beads are incubated with a cell lysate containing c-Myc tagged protein, the fusion protein is captured, and the beads are subsequently washed and then eluted using low-pH elution buffer or non-reducing sample buffer. The protocol and buffers have been optimized for both IP and co-IP reactions, enriching for specific protein interaction complexes in the eluted samples. Anti-c-Myc antibody can be used to detect c-Myc tagged protein by Western blot analysis.

For information about the binding capacity and other properties of the magnetic beads used in this kit, see Pierce Anti-c-Myc Magnetic Beads (Part No. 88842).

Related Products
Pierce™ c-Myc-Tag IP/Co-IP Kit

Pierce™ Phosphoprotein Phosphate Estimation Assay Kit (Thermo Scientific™)

The Thermo Scientific Phosphoprotein Phosphate Estimation Kit enables classification and identification of proteins as phosphorylated (serine and threonine), as well as semi-quantitative assessment of the phosphorylation level.

Features of the Phosphoprotein Phosphate Estimation Kit:

Specific—measures phosphoserine (p-Ser) and phosphothreonine (p-Thr) only; does not measure phosphotyrosine (p-Tyr)
Convenient—test tube and 96-well microplate protocols included and require less than 90 minutes to perform
Semi-quantitative—calculate moles of phosphate (P) per mole of protein using the included phosvitin standard
Customizable—format is adaptable to development of specific assays for pure phosphoproteins when previously characterized standards are available

The Phosphoprotein Phosphate Estimation Assay Kit is designed to aid in characterization of the status and extent of phosphorylation of purified protein samples. The assay is based on the alkaline hydrolysis of phosphate from seryl and threonyl residues in phosphoproteins and quantification of the released phosphate with malachite green and ammonium molybdate. The assay is easily performed in 96-well microplates or test tubes and is completed in about one hour.

Applications:
• Identify proteins as containing phosphoserine or phosphothreonine phosphorylations
• Estimate the amount of pS and pT phosphorylation
• Develop specific quantitative assays for well-characterized phosphoproteins of interest

The assay can be used to identify whether a purified protein contains either phospho-serine (p-Ser) or phospho-threonine (p-Thr) as well as to estimate the level of this type of phosphorylation. For quantitation, the test protein sample is compared with specific concentrations of phosvitin, a phosphoprotein of known phosphorylation level. The alkaline hydrolysis step does not release phosphate from phospho-tyrosine (p-Tyr) residues in peptide linkage. Therefore, a negative result for an unknown purified protein preparation indicates that the protein is either (1) not a phosphoprotein or (2) is phosphorylated exclusively at tyrosine residues. In the latter case, Western blot analysis using an anti-phosphotyrosine antibody will be necessary to distinguish between these two possibilities.

Pierce™ Coomassie Plus (Bradford) Assay Reagent (Thermo Scientific™)

The Thermo Scientific Pierce Coomassie Plus Protein Assay is a ready-to-use, reducing agent-compatible, improved Bradford assay reagent to quickly measure (A595nm) total protein concentration compared to a protein standard.

The Pierce Coomassie Plus Assay Reagent is a single, ready-to-use solution for measuring protein concentration. Simply add the reagent to equal volumes of samples and standards, mix and then measure the absorbance at 595nm. The assay costs only pennies per sample and can be performed in either test tube or microplate format. The Pierce Coomassie Plus Assay Reagent provides increased linearity of response and only half the protein-to-protein variability of other commercial Bradford assay formulations.

Features of the Coomassie Plus Protein Assay:

Colorimetric—measure with a standard spectrophotometer or plate reader (595nm)
Easy to use—single reagent; no working reagent preparation required
Fast—almost immediate color development; add, mix and read results
Broad range—detects protein concentration in the range 1 to 1500 µg/mL
Better—improved linearity and response-uniformity compared to traditional Bradford formulations
Flexible—microplate and cuvette protocols provided with the instructions and adaptable to several target working ranges

How the Coomassie Plus (Bradford) Assay Detects Protein
Use of coomassie G-250 dye in a colorimetric reagent for the detection and quantitation of total protein was first described by Dr. Marion Bradford in 1976. In the acidic environment of the reagent, protein binds to the coomassie dye. This results in a spectral shift from the reddish/brown form of the dye (absorbance maximum at 465nm) to the blue form of the dye (absorbance maximum at 610nm). The difference between the two forms of the dye is greatest at 595nm, so that is the optimal wavelength to measure the blue color from the coomassie dye-protein complex. If desired, the blue color can be measured at any wavelength between 575nm and 615nm. At the two extremes (575nm and 615nm) there is a loss of about 10% in the measured amount of color (absorbance) compared to that obtained at 595nm.

Development of color in coomassie dye-based (Bradford) protein assays has been associated with the presence of certain basic amino acids (primarily arginine, lysine and histidine) in the protein. Van der Waals forces and hydrophobic interactions also participate in the binding of the dye by protein. The number of Coomassie dye ligands bound to each protein molecule is approximately proportional to the number of positive charges found on the protein. Free amino acids, peptides and low molecular weight proteins do not produce color with coomassie dye reagents. In general, the mass of a peptide or protein must be at least 3,000 daltons to be assayed with this reagent. The assay is performed at room temperature and no special equipment is required. Simply add the sample to the tube containing reagent and the resultant blue color is measured at 595nm following a short room-temperature incubation. The coomassie dye containing protein assay is compatible with most salts, solvents, buffers, thiols, reducing substances and metal chelating agents encountered in protein samples.

For more information, see the article "Chemistry of Protein Assays" in the Protein Methods Library.

Related Products
Pierce™ Coomassie Plus (Bradford) Assay Kit
Pierce™ Detergent Compatible Bradford Assay Kit

InsuQuant Mass Spectrometric Kit (Thermo Scientific™)

Simplify your affinity purification workflow with the Thermo Scientific™ InsuQuant™ Mass Spectrometric Kit, an exclusive pre-analytical solution designed to simultaneously detect, differentiate, and quantify endogenous and exogenous insulin types.

SphingoStrips™ Membranes (Invitrogen™)

SpingoStrips™ membranes are designed for the identification of proteins possessing phosphoinositide or sphingolipid recognition domains and for analysis of their lipid-binding specificities.

Micro BCA™ Reagent A (MA) (Thermo Scientific™)

Thermo Scientific Pierce Micro BCA Reagent A (MA) is a proprietary alkaline tartrate-carbonate buffer. This product is sufficient for 3200 microplate assays when mixed with Reagents MB and MC.

Related Products
Micro BCA™ Protein Assay Kit
Micro BCA™ Reagent B (MB)
Micro BCA™ Reagent C (MC)

Pierce™ His Protein Interaction Pull-Down Kit (Thermo Scientific™)

Thermo Fisher Scientific Pierce His Tag Protein Interaction Pull-Down Kit contains the necessary components to capture and purify proteins that interact with His-tagged fusion proteins.

Features of His Tag Protein Interaction Pull-Down Kit:

6xHis pull-down (Product No. 21277)—purifies protein interactors of any His-tagged fusion protein
Complete kits—provide all components and detailed protocol for purifying protein:protein interactions
No special equipment needed—use common laboratory equipment and reagents (e.g., microcentrifuge)
Convenient—microcentrifuge spin columns facilitate simple and efficient manipulation of agarose beads, including simple processing of multiple samples
Flexible—instructions include protocols for use with bait and prey proteins expressed from a variety of sample types
Less non-specific binding—Cobalt chelate resin is more specific for histidine-tagged fusion proteins than nickel resins, resulting in less non-specific binding
Binding—Binds 10 to 25 mg of histidine-tagged fusion protein per mL of resin

Applications:

• Discover a new protein:protein interaction from a cell lysate
• Confirm a putative interaction from a cell lysate or with a previously purified protein
• Extract protein:protein interaction information from in vitro transcription/translation lysates

You provide the tagged fusion protein as the "bait" and the cells expressing the putative protein interaction target ("prey"), and the Pull-Down Kits provide everything else: cell lysis buffer, microcentrifuge spin columns, tag-specific affinity resin (agarose beads) and optimized buffers and protocol. The Pull-Down Kits are designed to teach the method to first-time users and to increase ease-of-use, convenience and reproducibility for experienced researchers.

Related Products
Pierce™ GST Protein Interaction Pull-Down Kit

Pierce™ BCA Protein Assay Reagent A (Thermo Scientific™)

BCA Protein Assay Reagent A is a component of the Thermo Scientific Pierce BCA Protein Assay Kit, a two-component, high-precision, detergent-compatible assay reagent set to measure (A562nm) total protein concentration compared to a protein standard.

Used in more labs than any other detergent-compatible protein assay, Pierce BCA Reagents provide accurate determination of protein concentration with most sample types encountered in protein research. The Pierce BCA Assay can be used to assess yields in whole cell lysates and affinity-column fractions, as well as to monitor protein contamination in industrial applications. Compared to most dye-binding methods, the BCA Assay is affected much less by protein compositional differences, providing greater protein-to-protein uniformity.

Features of the Thermo Scientific Pierce BCA Protein Assay Kit (reagents A and B) :

Colorimetric—estimate visually or measure with a standard spectrophotometer or plate reader (562nm)
Excellent uniformity—exhibits less protein-to-protein variation than dye-binding methods
Compatible—unaffected by typical concentrations of most ionic and nonionic detergents
Moderately fast—much easier and four times faster than the classical Lowry method
High linearity—linear working range for BSA equals 20 to 2000 µg/mL
Sensitive—detect down to 5 µg/mL with the enhanced protocol

Applications:
• Studying protein:protein interactions
• Measuring column fractions after affinity chromatography
• Estimating percent recovery of membrane proteins from cell extracts
• High-throughput screening of fusion proteins

How the BCA Protein Assay Detects Protein:
The BCA Protein Assay combines the well-known reduction of Cu2+ to Cu1+ by protein in an alkaline medium with the highly sensitive and selective colorimetric detection of the cuprous cation (Cu1+) by bicinchoninic acid. The first step is the chelation of copper with protein in an alkaline environment to form a light blue complex. In this reaction, known as the biuret reaction, peptides containing three or more amino acid residues form a colored chelate complex with cupric ions in an alkaline environment containing sodium potassium tartrate.

In the second step of the color development reaction, bicinchoninic acid (BCA) reacts with the reduced (cuprous) cation that was formed in step one. The intense purple-colored reaction product results from the chelation of two molecules of BCA with one cuprous ion. The BCA/copper complex is water-soluble and exhibits a strong linear absorbance at 562 nm with increasing protein concentrations. The BCA reagent is approximately 100 times more sensitive (lower limit of detection) than the pale blue color of the first reaction.

The reaction that leads to BCA color formation is strongly influenced by four amino acid residues (cysteine or cystine, tyrosine, and tryptophan) in the amino acid sequence of the protein. However, unlike the Coomassie dye-binding methods, the universal peptide backbone also contributes to color formation, helping to minimize variability caused by protein compositional differences.

For more information, see the article "Chemistry of Protein Assays" in the Protein Methods Library.

Related Products
Pierce™ BCA Protein Assay Kit
Pierce™ BCA Protein Assay Reagent B
Pierce™ BCA Solid

Pierce™ Microplate BCA Protein Assay Kit - Reducing Agent Compatible (Thermo Scientific™)

This BCA Protein Assay Kit is the reducing agent-compatible version of our popular Thermo Scientific Pierce BCA Protein Assay. The kit enables you to measure protein concentration in samples that contain thiol-reductants dithiothreitol (DTT) and 2-mercaptoethanol (BME), and comes with 20 96-well microplates.

Features of the Microplate BCA Protein Assay Kit—Reducing Agent Compatible:

Compatible—assay samples that contain up to 5 mM DTT, 35 mM BME, or 10 mM TCEP
BCA technology—only a slight modification of the standard BCA Protein Assay protocol (15-minute incubation with Compatibility Reagent); no precipitation steps required
Small samples—requires only 25 µL (standard kit) or less than 10 µL (microplate kit) of sample
Colorimetric—measure with a standard spectrophotometer or plate reader (562nm)
Excellent uniformity—exhibits less protein-to-protein variation than dye-binding methods
High linearity—linear working range for BSA equals 125 to 2000 µg/mL

The BCA Protein Assay Kit—Reducing Agent Compatible (BCA-RAC) provides all of the advantages of the original BCA Assay, plus compatibility with disulfide reducing agents at concentrations routinely used in protein sample buffers. This special adaptation of the popular Pierce BCA Protein Assay method enables accurate protein concentration measurement for samples containing DTT, 2-ME or TCEP. This reducing agent compatible (RAC) BCA Kit extends the already broad reagent compatibility of the BCA Protein Assay protocol to include nearly all types of components commonly present in protein research samples.

Related Products
Pierce™ BCA Protein Assay Kit - Reducing Agent Compatible
96-Well Plates for Pierce™ BCA-RAC Assay
Ampule Breakers

Pierce™ 660nm Protein Assay Reagent (Thermo Scientific™)

The Thermo Scientific Pierce 660 nm Protein Assay is a ready-to-use, detergent- and reducing agent-compatible assay reagent to quickly measure (A660 nm) total protein concentration compared to a protein standard.

The Pierce 660 nm Assay is more linear than coomassie-based Bradford assays and compatible with higher concentrations of most detergents, reducing agents and other commonly used reagents. The accessory Ionic Detergent Compatibility Reagent (IDCR) provides for even broader detergent compatibility, making this one of the only protein assays that is suitable for samples containing Laemmli SDS sample buffer with bromophenol blue. Although the Pierce 660 nm Protein Assay produces a higher level of protein-to-protein variation (37%) than other assays, such as the BCA Protein Assay, the simpler single-reagent format and broader substance compatibility make the Pierce 660 nm Assay more convenient for many routine applications. The Pierce 660 nm Protein Assay can be performed in either a test tube or microplate format.

Features of the 660 nm Protein Assay Reagent:

Versatile—works with a greater range of detergents and reducing agents than other dye-based assays
Fast—single reagent with a simple mix-and-read protocol; no working reagent to prepare
Accurate—produces standard curves that are more linear than with the Bradford assay method
Flexible—assay may be performed in test tubes or microplates
Conserve samples—requires only 10 µL for microplate or 100 µL for the test tube procedures
Convenient—room temperature storage means no waiting for reagent equilibration before use

How the Pierce 660nm Assay Detects Protein:
The Pierce 660nm Protein Assay is based on the binding of a proprietary dye-metal complex to protein in acidic conditions that causes a shift in the dye's absorption maximum, which is measured at 660nm. The dye-metal complex is reddish-brown and changes to green upon protein binding. The color change is produced by deprotonation of the dye at low pH facilitated by interactions with positively charged amino acid groups in proteins. Therefore, the dye interacts mainly with basic residues in proteins, such as histidine, arginine and lysine and to a lesser extent tyrosine, tryptophan and phenylalanine.

The color produced in the assay is stable and increases in proportion to a broad range of increasing protein concentrations, even in the presence of detergents and reducing agents that would be incompatible with Bradford and BCA Protein Assays. The optional IDCR may be added to the assay reagent to increase compatibility with high amounts of ionic detergents, allowing samples containing Laemmli SDS sample buffer with bromophenol blue to be measured. The IDCR completely dissolves by thorough mixing and does not have any effect on the assay.

For more information, see the article "Chemistry of Protein Assays" in the Protein Methods Library.

Related Products
Pierce™ 660nm Protein Assay Kit
Ionic Detergent Compatibility Reagent for Pierce™ 660nm Protein Assay Reagent

LightShift™ Poly (dI-dC) (Thermo Scientific™)

Thermo Scientific LightShift Poly(dI-dC) can be used as competitor for nonspecific DNA binding proteins.

More Product Data
Transfer EMSA gels using the Pierce G2 Fast Blotter

Related Products
LightShift™ Chemiluminescent EMSA Kit
LightShift™ EMSA Optimization and Control Kit

PIP Strips™ Membranes (Invitrogen™)

PIP Strips™ membranes are designed for the identification of proteins possessing phosphoinositide recognition domains and for analysis of their lipid-binding specificities. PIP Strips™ membranes facilitate the analysis of phosphoinositide protein interactions by protein-lipid overlay assays. Proteins may be detected using standard western blot procedures in conjunction with high-performance alkaline phosphatase- and horseradish peroxidase (HRP)-mediated signal generation systems.

Quant-iT™ Protein Assay Kit (Invitrogen™)

The Quant-iT Protein Assay Kit makes protein quantitation easy and accurate. The kit provides concentrated assay reagent, dilution buffer, and pre-diluted BSA standards. Simply dilute the reagent, load it into the wells of a microplate, add 1-20 µL of sample, mix, then measure the fluorescence. The assay is highly selective for protein and exhibits very little protein-to-protein variation. The assay is performed at room temperature, and the signal is stable for 3 hours. Common contaminants, such as salts, solvents, or DNA—but not detergents—are well tolerated in the assay. Quant-iT DNA Assay Kits (Q33120, Q33130) and a Quant-iT RNA Assay Kit (Q33140) are also available.

Pierce™ GST Protein Interaction Pull-Down Kit (Thermo Scientific™)

Thermo Fisher Scientific Pierce GST Tag Protein Interaction Pull-Down Kits contains the necessary components to capture and purify proteins that interact with GST-tagged fusion proteins.

Features of GST Tag Protein Interaction Pull-Down Kit:

GST pull-down (Product No. 21516)—gently purifies protein interactors of any GST-tagged fusion protein without denaturing
Complete kits—provide all components and detailed protocol for purifying protein:protein interactions
No special equipment needed—use common laboratory equipment and reagents (e.g., microcentrifuge)
Convenient—microcentrifuge spin columns facilitate simple and efficient manipulation of agarose beads, including simple processing of multiple samples
Flexible—instructions include protocols for use with bait and prey proteins from many different sources
Binding—Binds approx. 8 mg of GST-tagged fusion protein per mL of resin

Applications:
• Discover a new protein:protein interaction from a cell lysate
• Confirm a putative interaction from a cell lysate or with a previously purified protein
• Extract protein:protein interaction information from in vitro transcription/translation lysates

You provide the tagged fusion protein as the "bait" and the cells expressing the putative protein interaction target ("prey"), and the Pull-Down Kits provide everything else: cell lysis buffer, microcentrifuge spin columns, tag-specific affinity resin (agarose beads) and optimized buffers and protocol. The Pull-Down Kits are designed to teach the method to first-time users and to increase ease-of-use, convenience and reproducibility for experienced researchers.

Related Products
Pierce™ His Protein Interaction Pull-Down Kit

Micro BCA™ Protein Assay Kit (Thermo Scientific™)

The Thermo Scientific Pierce Micro BCA Protein Assay Kit is a special 3-component version of our popular BCA Reagents, optimized to measure (A562nm) total protein concentration of dilute protein solutions (0.5 to 20 micrograms/mL).

Features of the Micro BCA Protein Assay Kit:

Sensitive—accurately detect down to 0.5 µg/mL (2 µg/mL in microplate format)
High linearity—linear working range for BSA equals 0.5 to 20 µg/mL
Colorimetric—measure with a standard spectrophotometer or plate reader (562nm)
Compatible—unaffected by typical concentrations of most ionic and nonionic detergents
Convenient—microplate and cuvette protocols provided with the instructions
Stable—kit stable at room temperature; prepared working reagent stable for to 24 hours

The Micro BCA Protein Assay Kit is a specialized version of the popular Pierce BCA Protein Assay for determining the protein concentration of dilute samples. Mixing together the three Micro BCA Reagents results in a working solution that is sufficiently concentrated to measure protein when mixed with an equal volume of sample. The result is an assay for accurately measuring 0.5 to 20 µg/mL protein solutions. The assay is exceptionally linear and exhibits very low levels of protein-to-protein variability.

Related Products
Micro BCA™ Reagent A (MA)
Micro BCA™ Reagent B (MB)
Micro BCA™ Reagent C (MC)
Ampule Breakers

Pierce™ Rapid Antibody Isotyping Kit - Mouse (Thermo Scientific™)

The Thermo Scientific Pierce Rapid Mouse Antibody Isotyping Kit is a single-use, cassette-based kit for 5-minute lateral-flow assay determination of mouse monoclonal antibody class and subclass identity.

This antibody isotyping kit uses cartridges that provide a color-readout of the monoclonal antibody isotype within five minutes after pipetting a small amount of diluted culture supernatant or ascites fluid sample into the sample well. The kit determines mouse IgG1, IgG2a, IgG2b, IgG3, IgA, IgM.

Features of the Pierce Rapid Mouse Antibody Isotyping Kit:

Long shelf life—stable for at least one year at room temperature
Single-step—add diluted antibody sample to the loading-well of cassette
Fast—within 5 minutes a band appears that indicates the antibody isotype
Sensitive—detect antibodies in tissue culture media or ascites fluid samples at any concentration greater than 10 ng/mL
Specific—assay does not cross-react with fetal bovine serum (FBS)
Reliable—results are similar to the standard ELISA-based isotyping assays

Each Pierce Rapid Isotyping Kit assay is performed by simply adding a properly diluted tissue culture supernatant or mouse ascites sample to the well of the small cassette. Gold conjugates embedded in the cassette form specific class- and subclass-soluble complexes with the antibodies in the sample. These complexes travel the length of the membrane and are resolved on the anti-isotype and class-specific antibody-impregnated membrane. Results are displayed as a red band indicating the antibody isotype or subclass.

Determining the class and subclass of a monoclonal antibody is useful in planning the best immunoglobulin purification method. For example, mouse IgA and IgM are best purified by size (i.e., gel exclusion) or using immunoaffinity separation columns. Mouse IgG2a and IgG2b are purified with immobilized Protein A at pH 7-8, while Mouse IgG1 binds best to Protein A at pH 8-9. Immunoglobulin that contains kappa light chains can be purified using immobilized Protein L.

The Pierce Rapid Isotyping Kit is compatible with both tissue culture supernatant and mouse ascites fluid, and is more sensitive than conventional latex-bead based dipstick assays and much faster than ELISA-based isotyping assays. The kit requires only 0.5µL ascites fluid, 5 to 55µL of cell culture supernatant or 1.5ng of purified antibody.

Related Products
Rapid ELISA Mouse mAb Isotyping Kit
Pierce™ Rapid Antibody Isotyping Kit plus Kappa and Lambda - Mouse

ProQuest™ Two-Hybrid System with Gateway™ Technology (Invitrogen™)

The ProQuest™ Two-Hybrid System with Gateway® Technology is an in vivo yeast-based system for identifying interactions between two proteins. This interaction reconstitutes a functional transcription factor that activates chromosomally integrated reporter genes where transcriptional activation is monitored by the growth of cells on selective media.
The ProQuest™ System features:
• Gateway® Technology to allow rapid and easy generation of bait and prey constructs, and to facilitate downstream application
• Low copy-number DBD (DNA Binding Domain) and AD (Activation Domain) vectors (ARS/CEN) to control over-expression and increase reproducibility
• Three different reporter genes (HIS3, URA3, and lacZ) with independent promoter regions to rapidly weed out false positives. URA3 reporter gene allows for both positive and negative selection, enabling advanced two-hybrid techniques such as reverse two-hybrid.

• A set of strong-to-weak Gateway®-based control interactions to evaluate results and assess the strength of the interaction being tested

Pierce™ Chromogenic Endotoxin Quant Kit (Thermo Scientific™)

The Thermo Scientific Pierce Chromogenic Endotoxin Quant Kit is a highly sensitive endpoint assay that accurately measures and detects endotoxin (lipopolysaccharide) in a protein, peptide, nucleic acid, or antibody sample using the amebocyte lysate assay. The kit enables detection within two linear sensitivity ranges of 0.01–0.1 EU/mL and 0.1–1.0 EU/mL.

Features and benefits of the Pierce Chromogenic Endotoxin Quant Kit include:
Highly sensitive with a broad range—detect as little as 0.01 EU/mL to 1 EU/mL
Specific—no interference from ß-glucans and suitable for wide range of samples, including protein, vaccine, plasmid, DNA, RNA
Fast—perform assay in as little as 20 minutes
End-point chromogenic assay—measure with a standard spectrophotometer or plate reader at 405–410 nm

The Pierce Chromogenic Endotoxin Quant Kit is an end-point chromogenic endotoxin detection assay based on the amebocyte lysate method, which measures endotoxin through the interaction of the endotoxin with the proenzyme Factor C found in circulating amebocytes of the horseshoe crab. The proteolytic activity of this proenzyme is activated in the presence of lipopolysaccharides (endotoxins) derived from the outer cell membrane of gram-negative bacteria such as E.coli. Endotoxin levels are determined by measuring the activity of Factor C in the presence of a synthetic peptide substrate that releases p-nitroaniline (pNA) after proteolysis, producing a yellow color that can be measured at an absorbance of 405 nm.

Endotoxin levels in the samples are accurately determined using the included endotoxin standard of known concentration that is derived from E.coli strain O111: B4. Determining endotoxin levels is important to assess the efficiency of endotoxin removal methods and prevent endotoxic shock, inflammation, and/or sepsis in tissue culture cells and animals injected with endotoxin-contaminated proteins.

Applications: quantitation of endotoxin levels in a protein, peptide, antibody, or nucleic acid samples

Related products:
Pierce High Capacity Endotoxin Removal Resin
Pierce High Capacity Endotoxin Removal Spin Columns

Compat-Able™ Coomassie Plus Protein Assay Kit (Thermo Scientific™)

The Thermo Scientific Compat-Able Coomassie Plus Protein Assay Kit eliminates interfering substances from protein assay samples to make them compatible with BCA and Bradford assays.

The Compat-Able Reagents remove salts, detergents, reducing agents and other substances from protein samples to eliminate interference with protein assays. The protocol selectively precipitates all of the protein, thereby allowing the non-protein components to be easily decanted and removed. The purified, precipitated protein is redissolved in water, making it ready for accurate determination of the protein concentration by standard protein assay methods. The procedure is accomplished in less than 10 minutes with just a few simple steps. The Compat-Able Preparation Set is available individually or conveniently bundled with either the Thermo Scientific Pierce BCA Protein Assay Kit or the Thermo Scientific Pierce Coomassie Plus Protein Assay Kit.

Features of the Compat-Able Protein Assay Preparation Reagent Kit:

Eliminate incompatibilities—removes nearly any substance that interferes with colorimetric protein assays: salts, detergents, denaturants, reducing agents, and even IEF sample buffer
Simple and fast—prepare samples in less than 10 minutes with four simple steps
Convenient—reagent set is easier to use than homemade TCA or acetone precipitation reagents, thereby producing more consistent results
Scalable—microcentrifuge method is easily scaled to larger centrifuge tube volumes for special needs
Validated—tested and offered together with BCA and Coomassie Plus Protein Assay Kits; protocol integrates control and normalization procedures

Related Products
Compat-Able™ Protein Assay Preparation Reagent Kit
Compat-Able™ BCA Protein Assay Kit
Pierce™ Detergent Compatible Bradford Assay Kit

Pro-Detect™ Rapid V5 Competitive Assay Kit (Thermo Scientific™)

The Thermo Scientific Pro-Detect Rapid V5 Competitive Assay Kit is a single-use, dipstick lateral flow kit for quick, easy detection of V5-tagged proteins in protein expression and purification systems. This lateral flow assay uses membrane-based strips coated with dye-bound conjugated antibodies specific to V5 tag to provide a qualitative detection within ten minutes. This assay can be used to detect V5-tagged proteins directly from cell culture media (supernatant) or cell lysates without any special instrumentation or handling.

Features of the Pro-Detect Rapid competitive assay kits:
Easy to adopt—lateral flow strips can be used early in and throughout expression to monitor and confirm expression of desired protein-tagged target
Simple, fast method—simply dilute sample using provided diluent and dip in the lateral flow strip for qualitative results within 5-10 minutes
Sensitive—detect protein tags in supernatant or cell lysate samples down to low µg/mL concentrations
Specific—assay does not cross-react with common lysis and protein preparation reagents
Reliable—results are similar to other antibody immunoassays, including western blot and ELISA
Long shelf life—stable for at least one year at 4°C

Each Pro-Detect Rapid competitive assay is performed by simply adding a properly diluted tissue culture supernatant, lysate, or purified protein sample to a test tube or microplate well and dipping in a lateral flow strip. Gold-conjugated detection antibodies embedded in the strip form complexes with the tagged protein in the sample. In the presence of target protein tag, the dye-bound conjugated antibodies will bind to the tagged protein present in the sample instead of the protein tag bound at the test lines. Therefore, in a positive result, a competitive lateral flow assay will show decreasing intensity of the visible test lines until all test lines have disappeared. When there is no target protein tag present, the dye-bound conjugated antibodies specific to the target will bind at the test line(s), resulting in visual test lines in a negative result.

96-Well Plates for Pierce™ BCA-RAC Assay (Thermo Scientific™)

These are polystyrene 96-well round-bottom plates suitable for use with Thermo Scientific BCA-RAC (reducing agent compatible) assays.

Related Products
Pierce™ Microplate BCA Protein Assay Kit - Reducing Agent Compatible
Pierce™ BCA Protein Assay Kit - Reducing Agent Compatible

Pierce™ Classic Magnetic IP/Co-IP Kit (Thermo Scientific™)

The Thermo Scientific Pierce Classic Magnetic IP/Co-IP Kit enables highly effective and efficient immunoprecipitation (IP) and co-immunoprecipitation (co-IP) of antigens and protein-complexes using less than 10 µg of antibody and a magnetic separator.

Features of the Classic Magnetic IP/Co-IP Kit:

Compatible—magnetic beads based on Protein A/G recombinant protein ensures compatibility with most primary antibodies, whether from mouse or rabbit
Fast—immunoprecipitate in as few as 30 minutes to reduce background and improve the capture of transient protein complexes
Clean—immobilize your antibody to prevent contamination in your eluate
Resistant—no leaching of Protein A/G in the presence of detergents, low pH buffers or common mass spectrometry solvents
Efficient—immunoprecipitate with half the recommended volume of magnetic particles compared to other magnetic beads
Convenient—the comprehensive Co-IP kit contains the magnetic beads and all essential buffers to complete immunoprecipitation experiments

This immunoprecipitation kit uses high-quality Thermo Scientific Pierce Protein A/G Magnetic Beads and optimized buffers and flexible protocol to accomplish high-yield IP or co-IP with manual or automated magnetic-separation tools. The optimized Lysis/Wash Buffer optimizes yield and efficient binding of antibody-antigen and co-IP interactions. The relatively gentle, low-pH Elution Buffer dissociates the bound immune complex from the Protein A/G. Alternatively, the included Lane Marker Sample Buffer provides rapid, denaturing elution for direct SDS-PAGE analysis of IP products.

Includes:
Pierce Protein A/G Magnetic Beads, lysis/wash buffer, elution buffer, neutralization buffer and sample loading buffer

Immunoprecipitation with magnetic particles is performed much like IP with beaded agarose, except that separations are performed using a magnet rather than by centrifugation. The specific antibody is first added to the sample to form an immune complex that is then bound to the magnetic beads. The complex is washed to remove non-bound material and a low-pH elution buffer dissociates the bound immune complex from the Protein A/G. Alternatively, the Lane Marker Sample Buffer is included for dissociation using denaturing conditions or for downstream sample prep for SDS-PAGE analysis. The kit includes Thermo Scientific Pierce Protein A/G Magnetic Beads for fast and convenient magnetic isolation of antigens and optimized buffers for high antigen yield. The beads are removed from the solution manually using a magnetic stand or by automation with an instrument such as the Thermo Scientific KingFisher Flex Instrument.

It is generally known that longer antibody-sample incubations times (2 hours to overnight) usually provide greater yields in IP assays. It is often assumed that this greater yield comes with increased background. Our researchers have found that overnight antibody-sample binding followed by immunoprecipitation with the Pierce Classic Magnetic IP/Co-IP Kit does tend to increase yield but does not increase background. Thus, we recommend that researchers perform this binding step for at least 1 hour whenever possible.

Protocol Summary:
• Incubate cell lysate with IP antibody for 1 to 2 hours at room temperature or overnight at 4ºC.
• Bind antigen-antibody complex to Protein A/G magnetic beads for 1 hour at room temperature.
• Wash beads twice with IP Lysis/Wash Buffer and once with purified water.
• Elute the antigen/antibody complex.

Related Products
Pierce™ Classic IP Kit

CBQCA Protein Quantitation Kit (Invitrogen™)

The CBQCA Protein Quantitation Kit is a very sensitive assay for quantitating proteins in solution, capable of detection as low as 10 ng of protein per mL. Similar in sensitivity to our NanoOrange protein quantitation reagent (N-6666), CBQCA is better suited for accurate quantitation of proteins in the presence of lipids, membrane fractions or detergents, and for lipoproteins and small peptides.

Micro BCA™ Reagent B (MB) (Thermo Scientific™)

Thermo Scientific Pierce Micro BCA Reagent B (MB) is a proprietary bicinchonic acid solution. This product is sufficient for 3200 microplate assays when mixed with Reagents MA and MC.

Related Products
Micro BCA™ Protein Assay Kit
Micro BCA™ Reagent A (MA)
Micro BCA™ Reagent C (MC)

Compat-Able™ BCA Protein Assay Kit (Thermo Scientific™)

The Thermo Scientific Compat-Able BCA Protein Assay Kit eliminates interfering substances from protein assay samples to make them compatible with BCA and Bradford assays.

The Compat-Able Reagents remove salts, detergents, reducing agents and other substances from protein samples to eliminate interference with protein assays. The protocol selectively precipitates all of the protein, thereby allowing the non-protein components to be easily decanted and removed. The purified, precipitated protein is redissolved in water, making it ready for accurate determination of the protein concentration by standard protein assay methods. The procedure is accomplished in less than 10 minutes with just a few simple steps. The Compat-Able Preparation Set is available individually or conveniently bundled with either the Thermo Scientific Pierce BCA Protein Assay Kit or the Thermo Scientific Pierce Coomassie Plus Protein Assay Kit.

Features of the Compat-Able Protein Assay Preparation Reagent Kit:

Eliminate incompatibilities—removes nearly any substance that interferes with colorimetric protein assays: salts, detergents, denaturants, reducing agents, and even IEF sample buffer
Simple and fast—prepare samples in less than 10 minutes with four simple steps
Convenient—reagent set is easier to use than homemade TCA or acetone precipitation reagents, thereby producing more consistent results
Scalable—microcentrifuge method is easily scaled to larger centrifuge tube volumes for special needs
Validated—tested and offered together with BCA and Coomassie Plus Protein Assay Kits; protocol integrates control and normalization procedures

Related Products
Compat-Able™ Protein Assay Preparation Reagent Kit
Compat-Able™ Coomassie Plus Protein Assay Kit
Ampule Breakers

Easy-Titer™ Human IgG (gamma chain) Assay Kit (Thermo Scientific™)

The Thermo Scientific Easy-Titer Human IgG (gamma chain) Assay Kit includes antibody-sensitized microspheres to measure the specific concentration of antibodies by an easy and rapid microagglutination technique using standard microplates and UV-Vis plate reader (spectrophotometer). This kit is specific for the human IgG gamma chain and, unlike total protein assays, can specifically measure the concentration of target antibody in samples (e.g., serum, plasma, culture supernatant) that contain other proteins. It is sensitive, requiring very small sample volumes. Antibody concentration is determined from the assay response (absorbance) by comparison to a standard curve prepared using dilutions of a known antibody sample (sold separately).

General features of Easy-Titer Antibody Assay Kits:

Antibody-based specificity—measure concentration of target antibody in a sample, not just total protein; no need to purify antibody to assess its concentration
Faster and easier than ELISA—three-component, homogenous assay; 10 minutes total incubation time
No special equipment needed—uses standard vortex mixer, pipetter, 96-well microplate, plate shaker and reader (measure absorbance at 340nm or 400nm)
Sensitive—assay range (standard curve) 8 to 500 ng/mL; use sample at 15 to 300 ng/mL for optimal results
Reproducible—coefficient of variation < 5%; error depends on dilution and pipetting technique
Antibody standards sold separately—see product list for suggested products; use any antibody standard with proper target identity and known concentration (greater than 10 µg/mL)
Kits for five popular targets—choose a kit specific for a particular species and class of immunoglobulin; no cross-reaction with other species and classes of the target antibody

Easy-Titer Assay Kits detect and measure specific target antibodies using agglutination of microspheres that are coated ("sensitized") with the specific anti-IgG or IgM polyclonal antibodies. In the appropriate aqueous buffer (supplied in kit), the monodispersed antibody-coated microspheres (> 1 µM diameter) have highest absorptivity (λ-max) to incident light having a wavelength (340nm) that is equal to approximately half their diameter. When sample is added, two or more microspheres bind to each antibody target via their coated specific polyclonal antibodies, and this agglutination into effectively larger apparent spheres results in proportional decrease in absorptivity (lower absorbance).

Typical microagglutination assays depend on a change in light-scattering and corresponding change in transmittance, to which absorbance is inversely related. Easy-Titer Assay Kits use a special dilution buffer whose refractive index eliminates the effect of light-scattering on the monodispersed microspheres for the measurement wavelength used. Because of this, the final 10- to 20-fold dilution of the sample for use in the assay must be done using the Dilution Buffer supplied in the kit.

Easy-Titer Antibody Assays are faster and easier than ELISA:
• Prepare standards (5 to 500 ng/mL) by diluting purified antibody in Kit Dilution Buffer.
• Prepare samples by diluting in Dilution Buffer to within assay range (8 to 500 ng/mL).
• Vortex vial of microsphere beads to create homogeneous suspension.
• Pipette 20 µL of bead suspension and 20 µL of each sample and standard into 96-well microplate wells.
• Incubate microplate for 5 minutes with vigorous mixing.
• Add 100 µL of Kit Blocking Reagent.
• Incubate microplate for 5 minutes with vigorous mixing.
• Measure absorbance on standard plate reader (340nm or 405nm).
• Plot standard curve and interpolate samples to determine concentration.

Related Products
Easy-Titer™ Mouse IgG Assay Kit
Easy-Titer™ Rabbit IgG Assay Kit
Easy-Titer™ Human IgG (H+L) Assay Kit
Easy-Titer™ Human IgM Assay Kit

ProteinSEQ™ Protein A Quantitation Kit (Applied Biosystems™)

The ProteinSEQ™ Protein A Quantitation Kit contains all reagents and buffers needed for the PCR-based quantitation of Protein A leeched from Protein A purification columns. The kit utilizes TaqMan assay technology to deliver a quantitation method with the highest sensitivity and widest dynamic range of all methods currently available. The kit contains sufficient reagents for 200 reactions.

• Quantitate residual Protein A contaminants with ultra-high sensitivity
• Accelerate process development with more valid test results per run
• Reduce assay hands-on time with less sample dilution and preparation
• Achieve unprecedented productivity with near-5-log assay dynamic range

ProteinSEQ Protein A quantitation
The ProteinSEQ assay platform uses qPCR technology to measure protein process contaminants with extraordinary sensitivity and unparalleled dynamic range. Residual Protein A leeching from purification columns can be accurately measured from 2.56-8000 pg/mL, with outstanding quantitation efficiency and dilutional linearity.

Streamlined assay worflow
The ProteinSEQ Protein A Quantitation Kit is the only instrument platform-based Protein A quantitation solution to offer single-digit picogram sensitivity and nearly 5 logs of dynamic range. Laboratory workflow is greatly accelerated due to the reduction in the number of sample dilutions and replicates in each run.

What you get
The ProteinSEQ Protein A Quantitation Kit contains:
• Capture beads loaded with industry standard anti-Protein A antibody
• Protein A standards
• All reagents and buffers needed to enable PCR-based quantitation of Protein A

For a kit that does not include the capture beads and standards that may be used for customized Protein A measurements or for the quantitation of other purification ligands, please see the ProteinSEQ™ Protein A Core Kit (Cat. No. A28406).

Easy-Titer™ Human IgM Assay Kit (Thermo Scientific™)

The Thermo Scientific Easy-Titer Human IgM Assay Kit includes antibody-sensitized microspheres to measure the specific concentration of antibodies by an easy and rapid microagglutination technique using standard microplates and UV-Vis plate reader (spectrophotometer). This kit is specific for human IgM and, unlike total protein assays, can specifically measure the concentration of target antibody in samples (e.g., serum, plasma, culture supernatant) that contain other proteins. It is sensitive, requiring very small sample volumes. Antibody concentration is determined from the assay response (absorbance) by comparison to a standard curve prepared using dilutions of a known antibody sample (sold separately).

General features of Easy-Titer Antibody Assay Kits:

Antibody-based specificity—measure concentration of target antibody in a sample, not just total protein; no need to purify antibody to assess its concentration
Faster and easier than ELISA—three-component, homogenous assay; 10 minutes total incubation time
No special equipment needed—uses standard vortex mixer, pipetter, 96-well microplate, plate shaker and reader (measure absorbance at 340nm or 400nm)
Sensitive—assay range (standard curve) 8 to 500 ng/mL; use sample at 15 to 300 ng/mL for optimal results
Reproducible—coefficient of variation < 5%; error depends on dilution and pipetting technique
Antibody standards sold separately—see product list for suggested products; use any antibody standard with proper target identity and known concentration (greater than 10 µg/mL)
Kits for five popular targets—choose a kit specific for a particular species and class of immunoglobulin; no cross-reaction with other species and classes of the target antibody

Easy-Titer Assay Kits detect and measure specific target antibodies using agglutination of microspheres that are coated ("sensitized") with the specific anti-IgG or IgM polyclonal antibodies. In the appropriate aqueous buffer (supplied in kit), the monodispersed antibody-coated microspheres (> 1 µM diameter) have highest absorptivity (λ-max) to incident light having a wavelength (340nm) that is equal to approximately half their diameter. When sample is added, two or more microspheres bind to each antibody target via their coated specific polyclonal antibodies, and this agglutination into effectively larger apparent spheres results in proportional decrease in absorptivity (lower absorbance).

Typical microagglutination assays depend on a change in light-scattering and corresponding change in transmittance, to which absorbance is inversely related. Easy-Titer Assay Kits use a special dilution buffer whose refractive index eliminates the effect of light-scattering on the monodispersed microspheres for the measurement wavelength used. Because of this, the final 10- to 20-fold dilution of the sample for use in the assay must be done using the Dilution Buffer supplied in the kit.

Easy-Titer Antibody Assays are faster and easier than ELISA:
• Prepare standards (5 to 500 ng/mL) by diluting purified antibody in Kit Dilution Buffer.
• Prepare samples by diluting in Dilution Buffer to within assay range (8 to 500 ng/mL).
• Vortex vial of microsphere beads to create homogeneous suspension.
• Pipette 20 µL of bead suspension and 20 µL of each sample and standard into 96-well microplate wells.
• Incubate microplate for 5 minutes with vigorous mixing.
• Add 100 µL of Kit Blocking Reagent.
• Incubate microplate for 5 minutes with vigorous mixing.
• Measure absorbance on standard plate reader (340nm or 405nm).
• Plot standard curve and interpolate samples to determine concentration.

Related Products
Easy-Titer™ Mouse IgG Assay Kit
Easy-Titer™ Rabbit IgG Assay Kit
Easy-Titer™ Human IgG (H+L) Assay Kit
Easy-Titer™ Human IgG (gamma chain) Assay Kit

ProteinSEQ™ HCP Core Kit (Applied Biosystems™)

The ProteinSEQ™ HCP Core Kit is a customizable kit that enables users to customize their ProteinSEQ host cell protein measurements for their own cell lines. It contains buffers and reagents needed to perform 200 PCR reactions to quantify host cell proteins of any cell line for which there is an antibody available.

Features include:

• Precise—quantitate host cell protein contaminants with excellent precision
• Fast—helps accelerate process development with more valid test results per run
• Efficient—helps reduce hands-on time with less sample dilution and preparation
• Reproducible—achieve unprecedented productivity with 4-log dynamic range

ProteinSEQ CHO HCP quantitation
The ProteinSEQ assay platform uses qPCR technology to measure protein process contaminants with extraordinary sensitivity and unparalleled dynamic range. Host cell protein contaminants from any cell line can be measured easily and effectively by incorporating any anti-HCP antibody into the ProteinSEQ workflow.

Streamlined workflow
The ProteinSEQ HCP Core Kit is the only instrument platform-based HCP quantitation solution to deliver a customizable HCP assay with class-leading sensitivity and 4-log dynamic range. The kit helps accelerate laboratory workflows because the number of sample dilutions and replicates is reduced in each run.

Pierce™ 660nm Protein Assay Kit (Thermo Scientific™)

The Thermo Scientific Pierce 660 nm Protein Assay is a ready-to-use, detergent- and reducing agent-compatible assay reagent to quickly measure (A660 nm) total protein concentration compared to a protein standard.

The Pierce 660 nm Assay is more linear than coomassie-based Bradford assays and compatible with higher concentrations of most detergents, reducing agents and other commonly used reagents. The accessory Ionic Detergent Compatibility Reagent (IDCR) provides for even broader detergent compatibility, making this one of the only protein assays that is suitable for samples containing Laemmli SDS sample buffer with bromophenol blue. Although the Pierce 660 nm Protein Assay produces a higher level of protein-to-protein variation (37%) than other assays, such as the BCA Protein Assay, the simpler single-reagent format and broader substance compatibility make the Pierce 660 nm Assay more convenient for many routine applications. The Pierce 660nm Protein Assay can be performed in either a test tube or microplate format.

Features of the 660 nm Protein Assay Kit:

Versatile—works with a greater range of detergents and reducing agents than other dye-based assays
Fast—single reagent with a simple mix-and-read protocol; no working reagent to prepare
Accurate—produces standard curves that are more linear than with the Bradford assay method
Flexible—assay may be performed in test tubes or microplates
Conserve samples—requires only 10 µL for microplate or 100 µL for the test tube procedures
Convenient—room temperature storage means no waiting for reagent equilibration before use

How the Pierce 660 nm Assay Detects Protein:
The Pierce 660 nm Protein Assay is based on the binding of a proprietary dye-metal complex to protein in acidic conditions that causes a shift in the dye's absorption maximum, which is measured at 660 nm. The dye-metal complex is reddish-brown and changes to green upon protein binding. The color change is produced by deprotonation of the dye at low pH facilitated by interactions with positively charged amino acid groups in proteins. Therefore, the dye interacts mainly with basic residues in proteins, such as histidine, arginine and lysine and to a lesser extent tyrosine, tryptophan and phenylalanine.

The color produced in the assay is stable and increases in proportion to a broad range of increasing protein concentrations, even in the presence of detergents and reducing agents that would be incompatible with Bradford and BCA Protein Assays. The optional IDCR may be added to the assay reagent to increase compatibility with high amounts of ionic detergents, allowing samples containing Laemmli SDS sample buffer with bromophenol blue to be measured. The IDCR completely dissolves by thorough mixing and does not have any effect on the assay.

For more information, see the article "Chemistry of Protein Assays" in the Protein Methods Library.

Related Products
Pierce™ 660nm Protein Assay Reagent
Ionic Detergent Compatibility Reagent for Pierce™ 660nm Protein Assay Reagent

LightShift™ EMSA Optimization and Control Kit (Thermo Scientific™)

The Thermo Scientific LightShift EMSA Optimization and Control Kit is an extraordinarily robust and sensitive system for performing electrophoretic mobility shift assays (EMSA) to identify and characterize protein-DNA binding interactions. The kit includes reagents for setting up and customizing DNA binding reactions and a control set of DNA and protein extract to test the kit system.

Features of theLightShift EMSA Optimization and Control Kit:

• Excellent for detecting low-abundance proteins in nuclear extracts
• Sensitivity that surpasses radioactive and digoxigenin methods
• Compatible with previously established binding conditions for popular DNA-protein interactions
• Includes EBNA control system to help new users develop a working assay and understand the methods used to confirm binding interaction specificity

The principle for LightShift EMSA Detection is similar to a Western blot. Biotin end-labeled duplex DNA is incubated with a nuclear extract or purified factor and electrophoresed on a native gel. The DNA is then rapidly (30 minutes) transferred to a positive nylon membrane, UV crosslinked, probed with streptavidin-HRP conjugate and incubated with the substrate. The protocol from labeling to results can be accomplished in a single day.

The interaction of proteins with DNA is central to the control of many cellular processes including DNA replication, recombination and repair, transcription, and viral assembly. One technique that is central to studying gene regulation and determining protein:DNA interactions is the electrophoretic mobility shift assay (EMSA).

The EMSA technique is based on the observation that protein:DNA complexes migrate more slowly than free DNA molecules when subjected to non-denaturing polyacrylamide or agarose gel electrophoresis. Because the rate of DNA migration is shifted or retarded upon protein binding, the assay is also referred to as a gel shift or gel retardation assay. Until conception of the EMSA protein:DNA interactions were studied primarily by nitrocellulose filter-binding assays.

All that is needed to perform the assay is purified DNA target that has been end-labeled with biotin, the protein extract to be tested, nylon membrane and basic electrophoresis equipment. DNA targets can be synthesized with 5' or 3' biotin labels or they can be labeled after synthesis using the Thermo Scientific Biotin 3' End DNA Labeling Kit (Product No. 89818). Nuclear, cytosolic or whole cell protein extracts can be obtained by a variety of methods, including the Thermo Scientific NE-PER Nuclear and Cytoplasmic Extraction Reagent Kit (Product No. 78833).

More Product Data
Transfer EMSA gels using the Pierce G2 Fast Blotter

Related Products
LightShift™ Chemiluminescent EMSA Kit
LightShift™ Poly (dI-dC)

GlycoLink™ IP Kit (Thermo Scientific™)

The Thermo Scientific GlycoLink IP Kit provides components for effective immunoprecipitation (IP and co-IP) based on small-scale, covalent, affinity-resin immobilization of antibodies and other glycoproteins via oxidized sugar groups.

Features of the GlycoLink IP Kit:

Efficient immobilization—couple 2 to 10 µg of oxidized antibody or other glycoprotein to 20 µL of resin in 2 hours or less
Stable immobilization—resonance structure of the hydrazone bonds are sufficiently stable so the antibody remains coupled during elution
Preserves binding function—immobilizes IgG via the Fc region, thereby keeping both antigen binding sites available for capturing target
Versatile applications—immobilize any molecule that contains oxidizable sugars, including glycoproteins for use in purifying protein interaction binding partners

The GlycoLink Kit uses hydrazide-activated UltraLink Resin to immobilize and perform 25 IP or Co-IP assays with different antibodies or glycoprotein ligands. The method is ideal for polyclonal antibodies, which typically have abundant carbohydrates (glycosylation) on their Fc portions. Monoclonal antibodies that contain adequate carbohydrates are also effective. Antibodies immobilized by this hydrazide-to-carbohydrate method have unobstructed antigen-binding sites and optimal purification capability. The prepared glycoprotein or antibody columns can be regenerated and reused at least five times for immunoprecipitation, co-immunoprecipitation or pull-down affinity-purification without significant loss in binding capacity.

Applications:
• Immunoprecipitation followed by electrophoresis and excision of the protein for mass spectrometry or sequencing
• Immunoprecipitation and SDS-PAGE analysis of a protein with a molecular weight similar to the antibody's heavy or light chain
• Identification of binding partners of immobilized glycoprotein
• Co-immunoprecipitation for determining protein-protein interactions

Includes:
Kit contains resin, buffers and reagents for immobilization; desalting columns; IP lysis/wash and elution buffers for immunoprecipitation; microcentrifuge spin columns and collection tubes; and loading buffer for SDS-PAGE

The GlycoLink IP Kit method results in covalent attachment of oxidized sugar groups of an IP antibody (or any other glycoprotein with oxidizable carbohydrate groups) to the hydrazide resin. The antibody resin is then incubated with the sample that contains the protein antigen of interest, allowing the antibody-antigen complex to form. After washing to remove non-bound components of the sample, the antigen is recovered by dissociation from the antibody with elution buffer supplied in the kit. The entire procedure is performed in a microcentrifuge spin cup, allowing solutions to be fully separated from the resin with a brief centrifugation. Only the antigen is eluted by the procedure, enabling it to be identified and further analyzed without interference from antibody fragments.

More Product Data
Improved immobilization and conjugation of glycoproteins

Pierce™ Protein A/G Coated Plate IP Kit (Thermo Scientific™)

The Thermo Scientific Pierce Protein A/G Coated Plate IP Kit uses coated Protein A/G microplates to perform immunoprecipitation assays in 96-well plates without resins, beads, centrifugation or magnets.

Pierce Coated Plate IP Kits enable rapid immunoprecipitation of multiple samples without the usual tedium of pipetting, centrifuging and separating beaded affinity resin in individual microcentrifuge tubes. Immunoprecipitation is accomplished using coated 96-well microplates rather than beaded agarose resin. The plate format allows for faster processing of multiple samples.

Features of the Protein A/G Coated Plate IP Kit:

• Ready-to-use, high quality coated plates provide high capacity and consistency
• Plate format best suited for simultaneously processing multiple samples and their control conditions
• Faster, easier and more thorough washing than with traditional tube/resin IP methods
• Uses familiar and convenient ELISA tools (multichannel pipettors and plate washing); no tedious separation of supernatant from pelleted resin beads, and no tubes to open and close and centrifuge
• Coated plates are 96-well strip plates, convenient for experiments requiring only a partial plate
• Easy-to-follow instructions, including detailed explanation of appropriate controls

Applications:
• Rapid, trouble-free immunoprecipitation of multiple samples and their controls
• Immunoprecipitation when plate-based tools and techniques are preferred

Protein A and Protein G are different proteins that bind to immunoglobulins (primarily only IgG). Typically, Protein A is preferred for use with Rabbit polyclonal antibodies, while Protein G is preferred for use with mouse antibodies (especially monoclonals of the IgG1 subclass). Protein A/G is a recombinant of Protein A and Protein G that has the additive binding properties of both proteins. Compare Protein A, Protein G and other antibody-binding proteins.

Related Products
Pierce™ Streptavidin Coated Plate IP Kit

Pierce™ Crosslink IP Kit (Thermo Scientific™)

The Thermo Scientific Pierce Crosslink IP Kit adapts the traditional IP method to include reagents and protocol for crosslinking IP antibodies to Protein A/G agarose to enable antigen immunoprecipitation without antibody contamination.

The primary benefits resulting from these features are the ability to purify target protein without contamination by the antibody and the ability to more effectively wash and separate samples from the beaded agarose resin.

Features of the Crosslink IP Kit:

Eliminates antibody contamination—antibody is irreversibly attached to the agarose beads so that co-elution of heavy and light chains with the purified protein is minimized
Easy and efficient scalability—use only the amount of antibody needed for a single IP experiment or immobilize 100-200 µg of antibody to prepare ready-made IP affinity resin for many experiments
Assay reliability and sample handling—Pierce Spin Columns eliminate resin loss and provide for more efficient separation of solutions than traditional IP methods that use only microcentrifuge tubes
Prepared antibody affinity resin is reusable—because the antibody is covalently immobilized and usually is not inactivated by the mild elution procedure, the resin often can be used several times
Complete kits—package includes sufficient reagents and spin columns to perform at least 50 antibody immobilizations and IP experiments

Applications:
• Immunoprecipitation followed by electrophoresis and excision of the protein for mass spectrometry or sequencing identification analysis
• Immunoprecipitation and SDS-PAGE analysis of a target protein whose molecular weight is similar to the heavy or light chain antibody fragment
• Immunoprecipitation of target proteins for subsequent analysis by nondenaturing methods (i.e., methods not involving SDS-PAGE)

The Pierce Crosslink IP Kit method involves capturing the IP antibody to Protein A/G Agarose resin and covalently immobilizing it to the support by crosslinking with disuccinmidyl suberate (DSS). The antibody resin is then incubated with the sample that contains the protein antigen of interest, allowing the antibody:antigen complex to form. After washing to remove nonbound (presumably undesired) components of the sample, the antigen is recovered by dissociation from the antibody with elution buffer supplied in the kit. The entire procedure is performed in a microcentrifuge spin cup, allowing solutions to be fully separated from the agarose resin upon brief centrifugation. Only antigen is eluted by the procedure, enabling it to be identified and further analyzed without interference from antibody fragments. Furthermore, the antibody resin often can be reused for additional rounds of immunoprecipitation.

Related Products
Pierce™ Crosslink Magnetic IP/Co-IP Kit

Pierce™ Immunodiffusion Plates, Multiple Pattern (Thermo Scientific™)

Thermo Scientific Pierce Immunodiffusion Plates are standard Ouchterlony gel plates containing patterns of six wells around one well for studying and characterizing antibody-antigen binding interactions.

Features of Pierce Immunodiffusion Plates:

• Gelling agent contains precipitin brighteners for easy visualization
• Immunodiffusion plates contain diffusion enhancers to help speed the interaction process
• Excellent precipitin bands with antibodies from all species (including rabbit antibodies)
• Gels can be washed, dried and stained for a permanent record

Immunodiffusion (ID) is a classic technique for detecting antibody-antigen interactions based on the theory of double diffusion originally described by Oudin and Ouchterlony. Antigens and antibodies are placed into separate wells that are cut into a gel matrix and allowed to diffuse towards each other. If the reaction is positive, a precipitate forms that appears as an opaque line. The precipitation reaction occurs when the antigen and antibody concentrations are combined at near equivalent proportions.

When multivalent antigens combine with divalent antibodies in solution, three-dimensional lattices are formed that aggregate and precipitate. The amount of precipitate varies in proportion to the concentration of the antigen and antibody. At equivalent or optimal proportions almost all the antigen and antibody will precipitate. If there is an excess of antibody, the complexes formed with the antigen are insoluble. When there is an excess of antigen, the precipitate has a tendency to dissolve caused by the formation of soluble complexes.

Pierce™ Quantitative Peroxide Assay Kit (Lipid) (Thermo Scientific™)

The Thermo Scientific Pierce Quantitative Peroxide Assay Kit (lipid-compatible formulation) detects and measures hydrogen peroxide levels in biological samples using an iron and xylenol orange (XO) reagent.

This lipid-compatible peroxide assay kit detects peroxides based on oxidation of ferrous to ferric ion in the presence of xylenol orange. The kit's formulation may be used with lipid-containing samples without first extracting the lipids; however, because this kit does not contain sorbitol, the assay is less sensitive. Most proteins do not interfere with this assay, although some metal chelators may require use of a blank (i.e., control) to mitigate these effects.

Features of the Quantitative Peroxide Assay Kit:

Peroxides—detects and measures hydrogen peroxide (H2O2) levels in biological and other liquids samples
Convenient—no proprietary reagents involved but the ready-to-use kit removes the variability, difficulty and added expense of formulating the reagents yourself

Applications:
• General hydrogen peroxide (H2O2) measurement in protein samples
• Quantitation of peroxides in detergents
• Assessment of the effects of peroxides on cellular activity
• Determination of protein glycation; Measurement of peroxide accumulation in lipids

In this assay, hydroperoxides convert the Fe2+ to Fe3+ at acidic pH. With this lipid-compatible formulation, the peroxide converts the Fe2+ to Fe3+ directly. In a sulfuric acid solution, the Fe3+ complexes with the xylenol orange (XO) dye to yield a purple product having an absorbance maximum at 560nm. Peroxide levels in test samples can be determined by calculation from the known extinction coefficient of the XO-Fe complex or by reference to a standard curve prepared with hydrogen peroxide solution.

Related Products
Pierce™ Quantitative Peroxide Assay Kit (Aqueous)
Pierce™ Peroxide Assay Reagent A
Pierce™ Peroxide Assay Reagent B
Pierce™ Peroxide Assay Reagent C

Qubit™ Protein Assay Kit (Invitrogen™)

The Qubit Protein Assay Kit is designed specifically for use with the Qubit Fluorometer. Using between 1 and 20 µl of your sample, this assay can quantitate samples ranging from 12.5 µg⁄ml to 5 mg⁄ml and exhibits low protein to protein variation. The assay is highly selective for proteins and is designed to be accurate in the presence of reducing reagents, but not in the presence of a large amount of detergent. Common contaminants, such as reducing reagents (DTT, β-mercaptoethanol), salts, free nucleotides, amino acids, solvents, or DNA, but not detergents, are well tolerated in the assay. Slight protocol modifications are required for other contaminants. The kit provides concentrated assay reagent, dilution buffer, and pre-diluted BSA standards. Simply dilute the reagent using the buffer provided, add your sample (any volume between 1 µL and 20 µL is acceptable), and read the concentration.

Which product to choose for fluorometric protein quantitation?
• For 1–20 samples: use this Qubit Protein Assay Kit with the Qubit Fluorometer
• For 20–2000 samples: use the Quant-iT Protein Assay Kit with microplate reader

Notes:
1. All Qubit assay kits can be used with the Qubit 1.0, Qubit 2.0, Qubit 3, and Qubit 4 fluorometers.
2. 500 µL thin-walled PCR tubes are required but not included.

Pierce™ Bovine Gamma Globulin Standard Ampules, 2 mg/mL (Thermo Scientific™)

Thermo Scientific Pierce BGG Protein Assay Standards are high-quality reference samples for generating accurate standard curves and calibration controls in total protein assays.

Features of BGG Protein Assay Standards:

Convenient—1 mL ampules
Antibody standard—best reference standard for immunoglobulin quantitation in colorimetric protein assays
Bradford standard—best general protein standard in coomassie-based (Bradford) protein assays
Pure and stable—supplied in ultrapure 0.9% saline solution with 0.05% sodium azide; room temperature stable
Accurate and consistent—precisely formulated at 2.00 +/-0.03 mg/mL, ensuring excellent lot-to-lot consistency

These bovine gamma globulin (BGG) solutions are protein concentration reference standards for use in BCA, Bradford and other protein assay protocols. BGG is an accepted reference protein for total protein quantitation of purified antibodies or immunoglobulin-rich samples. The IgG standard is precisely formulated at 2 mg/mL in an ultrapure 0.9% sodium chloride (saline) solution. The concentration of the stock solution of purified BGG (Fraction II) is calibrated by direct comparison to an internal standard to ensure lot-to-lot consistency and accuracy.

Applications:
• Protein assay immunoglobulin quantitation standard (Coomassie-Bradford Assay, etc.)
• Antibody recovery control for desalting and other column procedures
• Loading control for SDS-PAGE
• General calibration of spectrophotometer UV-lamp (absorbance at 280nm)

Selection of a protein standard is potentially the greatest source of error in any protein assay. The best choice for an antibody quantitation standard is a purified, known concentration of the specific immunoglobulin being tested. Often this is not available or it is too expensive to use as a standard. In such cases, the best standard is one that will produce a representative color response curve with the selected protein assay and is readily available to any researcher. BGG provides this function for all kinds of immunoglobulin samples, including IgG.

For greatest accuracy in estimating total protein concentration in unknown samples, it is essential to include a standard curve each time the assay is performed. This is particularly true for the protein assay methods that produce non-linear standard curves. Deciding on the number of standards and replicates used to define the standard curve depends upon the degree of non-linearity in the standard curve and the degree of accuracy required. In general, fewer points are needed to construct a standard curve if the color response is linear. Typically, standard curves are constructed using at least two replicates for each point on the curve.

For added safety when opening glass ampules, consider using our Ampule Breakers, which are disposable safety devices that protect the fingers when breaking open a glass ampule.

Related Products
Pierce™ Bovine Gamma Globulin Standard Pre-Diluted Set

Pierce™ Direct IP Kit (Thermo Scientific™)

The Thermo Scientific Pierce Direct IP Kit uses an activated resin to covalently immobilize IP antibodies (any species or class) on agarose beads without the aid of Protein A/G, enabling immunoprecipitation without antibody interference.

The primary benefits resulting from this method are the opportunity to use any species or subclass of purified antibody (not just types that bind to Protein A or G) and the ability to purify target protein without contamination by the antibody. The method also makes it possible to immunoprecipitate antigens from serum samples without co-purifying non-target immunoglobulins. Finally, the kit uses microcentrifuge spin cups to effectively wash and separate samples from the beaded agarose resin.

Features of Direct IP Kit:

Requires less than 10 µg of antibody—optimized procedure requires only 2 to 10 µg of antibody for a single IP experiment, no more than is required for traditional IP methods
Easy and efficient scalability—use only the amount of antibody needed for a single immunoprecipitation or immobilize 100 to 200 µg of antibody to prepare ready-made IP affinity resin for many experiments
Minimal antibody contamination—antibody is irreversibly attached to the agarose beads so that co-elution of heavy and light chains with the purified protein is minimized (i.e., less than 5%)
IP with any species and subclass of antibody—Use chicken IgY, human IgE, mouse IgM or any other purified protein
Prepared antibody affinity resin is reusable—because the antibody is covalently immobilized and not inactivated by the mild elution procedure, the resin often can be used several times
Convenient sample handling—spin columns (see dimensions) eliminate resin loss and provide for efficient separation of solutions
Complete kit—package includes cell lysis buffer and sufficient reagents and spin columns to perform at least 50 antibody immobilizations and IP experiments
Requires purified antibody—IP antibody solution must be free of BSA, gelatin or other stabilizer proteins; for easy removal of these proteins, see our Antibody Clean-up Kit (Part No. 44600)

Applications:
• Immunoprecipitation followed by electrophoresis and excision of the protein for mass spectrometry or sequencing identification analysis
• Immunoprecipitation and SDS-PAGE analysis of a target protein whose molecular weight is similar to the heavy or light chain antibody fragment
• Immunoprecipitation of target proteins for subsequent analysis by nondenaturing methods (i.e., methods not involving SDS-PAGE)
• Immunoprecipitation with antibodies that do not bind to Protein A, Protein G or Protein A/G
• Immunoprecipitation from serum and other sample that contain immunoglobulins

Direct immunoprecipitation in two easy steps:

Step 1: Attach antibody to agarose resin: The first step in the Direct IP Method is to prepare the IP antibody affinity resin. Pure antibody (see Highlights) is incubated in phosphate buffer with an appropriate volume of AminoLink Plus Coupling Resin, an aldehyde-activated beaded agarose resin. During the incubation, various lysine epsilon-amines on the surface of the large antibody molecule react with aldehyde groups on the resin to form Schiff-base bonds that are then stabilized to secondary amine bonds in the presence of cyanoborohydride. The immobilization reaction, known as reductive amination, is nondenaturing and typically results in greater than 85% antibody coupling efficiency with minimal loss of antigen-binding function.

Step 2: Perform immunoprecipitation experiments: Once prepared, the antibody resin can be used in several parallel aliquots or in total for IP experiments. Antibody resin is incubated with a sample that contains the protein antigen of interest, allowing the antibody:antigen complex to form. After washing to remove nonbound (presumably undesired) components of the sample, the antigen is recovered by dissociation from the antibody with elution buffer supplied in the kit. The entire procedure is performed in a microcentrifuge spin cup, allowing solutions to be fully separated from the agarose resin upon brief centrifugation. Only antigen is eluted by the procedure, enabling it to be identified and further analyzed without interference from antibody fragments. Furthermore, the antibody resin can be reused for additional rounds of immunoprecipitation.

Related Products
Pierce™ Direct Magnetic IP/Co-IP Kit

Pierce™ Coomassie Plus (Bradford) Assay Kit (Thermo Scientific™)

The Thermo Scientific Pierce Coomassie Plus Protein Assay is a ready-to-use, reducing agent-compatible, improved Bradford assay reagent to quickly measure (A595nm) total protein concentration compared to a protein standard.

The Pierce Coomassie Plus Assay Reagent is a single, ready-to-use solution for measuring protein concentration. Simply add the reagent to equal volumes of samples and standards, mix and then measure the absorbance at 595nm. The assay costs only pennies per sample and can be performed in either test tube or microplate format. The Pierce Coomassie Plus Assay Reagent provides increased linearity of response and only half the protein-to-protein variability of other commercial Bradford assay formulations.

Features of the Coomassie Plus Protein Assay:

Colorimetric—measure with a standard spectrophotometer or plate reader (595nm)
Easy to use—single reagent; no working reagent preparation required
Fast—almost immediate color development; add, mix and read results
Broad range—detects protein concentration in the range 1 to 1500 µg/mL
Better—improved linearity and response-uniformity compared to traditional Bradford formulations
Flexible—microplate and cuvette protocols provided with the instructions and adaptable to several target working ranges

How the Coomassie Plus (Bradford) Assay Detects Protein
Use of coomassie G-250 dye in a colorimetric reagent for the detection and quantitation of total protein was first described by Dr. Marion Bradford in 1976. In the acidic environment of the reagent, protein binds to the coomassie dye. This results in a spectral shift from the reddish/brown form of the dye (absorbance maximum at 465nm) to the blue form of the dye (absorbance maximum at 610nm). The difference between the two forms of the dye is greatest at 595nm, so that is the optimal wavelength to measure the blue color from the coomassie dye-protein complex. If desired, the blue color can be measured at any wavelength between 575nm and 615nm. At the two extremes (575nm and 615nm) there is a loss of about 10% in the measured amount of color (absorbance) compared to that obtained at 595nm.

Development of color in coomassie dye-based (Bradford) protein assays has been associated with the presence of certain basic amino acids (primarily arginine, lysine and histidine) in the protein. Van der Waals forces and hydrophobic interactions also participate in the binding of the dye by protein. The number of Coomassie dye ligands bound to each protein molecule is approximately proportional to the number of positive charges found on the protein. Free amino acids, peptides and low molecular weight proteins do not produce color with coomassie dye reagents. In general, the mass of a peptide or protein must be at least 3,000 daltons to be assayed with this reagent. The assay is performed at room temperature and no special equipment is required. Simply add the sample to the tube containing reagent and the resultant blue color is measured at 595nm following a short room-temperature incubation. The coomassie dye containing protein assay is compatible with most salts, solvents, buffers, thiols, reducing substances and metal chelating agents encountered in protein samples.

For more information, see the article "Chemistry of Protein Assays" in the Protein Methods Library.

Related Products
Pierce™ Coomassie Plus (Bradford) Assay Reagent
Pierce™ Detergent Compatible Bradford Assay Kit
Ampule Breakers

Pierce™ BCA Protein Assay Kit (Thermo Scientific™)

The Thermo Scientific Pierce BCA Protein Assay Kit is a two-component, high-precision, detergent-compatible assay reagent set to measure (A562nm) total protein concentration compared to a protein standard. Used in more labs than any other detergent-compatible protein assay, Pierce BCA Reagents provide accurate determination of protein concentration with most sample types encountered in protein research. The Pierce BCA Assay can be used to assess yields in whole cell lysates and affinity-column fractions, as well as to monitor protein contamination in industrial applications. Compared to most dye-binding methods, the BCA Assay is affected much less by protein compositional differences, providing greater protein-to-protein uniformity.

Features of the BCA Protein Assay Kit:
• Colorimetric—estimate visually or measure with a standard spectrophotometer or plate reader (562nm)
• Excellent uniformity—exhibits less protein-to-protein variation than dye-binding methods
• Compatible—unaffected by typical concentrations of most ionic and nonionic detergents
• Moderately fast—much easier and four times faster than the classical Lowry method
• High linearity—linear working range for BSA equals 20 to 2000 µg/mL
• Sensitive—detect down to 5 µg/mL with the enhanced protocol

Applications:
• Studying protein:protein interactions
• Measuring column fractions after affinity chromatography
• Estimating percent recovery of membrane proteins from cell extracts
• High-throughput screening of fusion proteins

How the BCA Protein Assay Detects Protein:
The BCA Protein Assay combines the well-known reduction of Cu2+ to Cu1+ by protein in an alkaline medium with the highly sensitive and selective colorimetric detection of the cuprous cation (Cu1+) by bicinchoninic acid. The first step is the chelation of copper with protein in an alkaline environment to form a light blue complex. In this reaction, known as the biuret reaction, peptides containing three or more amino acid residues form a colored chelate complex with cupric ions in an alkaline environment containing sodium potassium tartrate.

In the second step of the color development reaction, bicinchoninic acid (BCA) reacts with the reduced (cuprous) cation that was formed in step one. The intense purple-colored reaction product results from the chelation of two molecules of BCA with one cuprous ion. The BCA/copper complex is water-soluble and exhibits a strong linear absorbance at 562 nm with increasing protein concentrations. The BCA reagent is approximately 100 times more sensitive (lower limit of detection) than the pale blue color of the first reaction.

The reaction that leads to BCA color formation is strongly influenced by four amino acid residues (cysteine or cystine, tyrosine, and tryptophan) in the amino acid sequence of the protein. However, unlike the Coomassie dye-binding methods, the universal peptide backbone also contributes to color formation, helping to minimize variability caused by protein compositional differences.

For more information, see the article "Chemistry of Protein Assays" in the Protein Methods Library.

Easy-Titer™ Rabbit IgG Assay Kit (Thermo Scientific™)

The Thermo Scientific Easy-Titer Rabbit IgG Assay Kit includes antibody-sensitized microspheres to measure the specific concentration of antibodies by an easy and rapid microagglutination technique using standard microplates and UV-Vis plate reader (spectrophotometer). This kit is specific for rabbit IgG and, unlike total protein assays, can specifically measure the concentration of target antibody in samples (e.g., serum, plasma, culture supernatant) that contain other proteins. It is sensitive, requiring very small sample volumes. Antibody concentration is determined from the assay response (absorbance) by comparison to a standard curve prepared using dilutions of a known antibody sample (sold separately).

General features of Easy-Titer Antibody Assay Kits:

Antibody-based specificity—measure concentration of target antibody in a sample, not just total protein; no need to purify antibody to assess its concentration
Faster and easier than ELISA—three-component, homogenous assay; 10 minutes total incubation time
No special equipment needed—uses standard vortex mixer, pipetter, 96-well microplate, plate shaker and reader (measure absorbance at 340nm or 400nm)
Sensitive—assay range (standard curve) 8 to 500 ng/mL; use sample at 15 to 300 ng/mL for optimal results
Reproducible—coefficient of variation < 5%; error depends on dilution and pipetting technique
Antibody standards sold separately—see product list for suggested products; use any antibody standard with proper target identity and known concentration (greater than 10 µg/mL)
Kits for five popular targets—choose a kit specific for a particular species and class of immunoglobulin; no cross-reaction with other species and classes of the target antibody

Easy-Titer Assay Kits detect and measure specific target antibodies using agglutination of microspheres that are coated ("sensitized") with the specific anti-IgG or IgM polyclonal antibodies. In the appropriate aqueous buffer (supplied in kit), the monodispersed antibody-coated microspheres (> 1 µM diameter) have highest absorptivity (λ-max) to incident light having a wavelength (340nm) that is equal to approximately half their diameter. When sample is added, two or more microspheres bind to each antibody target via their coated specific polyclonal antibodies, and this agglutination into effectively larger apparent spheres results in proportional decrease in absorptivity (lower absorbance).

Typical microagglutination assays depend on a change in light-scattering and corresponding change in transmittance, to which absorbance is inversely related. Easy-Titer Assay Kits use a special dilution buffer whose refractive index eliminates the effect of light-scattering on the monodispersed microspheres for the measurement wavelength used. Because of this, the final 10- to 20-fold dilution of the sample for use in the assay must be done using the Dilution Buffer supplied in the kit.

Easy-Titer Antibody Assays are faster and easier than ELISA:
• Prepare standards (5 to 500 ng/mL) by diluting purified antibody in Kit Dilution Buffer.
• Prepare samples by diluting in Dilution Buffer to within assay range (8 to 500 ng/mL).
• Vortex vial of microsphere beads to create homogeneous suspension.
• Pipette 20 µL of bead suspension and 20 µL of each sample and standard into 96-well microplate wells.
• Incubate microplate for 5 minutes with vigorous mixing.
• Add 100 µL of Kit Blocking Reagent.
• Incubate microplate for 5 minutes with vigorous mixing.
• Measure absorbance on standard plate reader (340nm or 405nm).
• Plot standard curve and interpolate samples to determine concentration.

Related Products
Easy-Titer™ Mouse IgG Assay Kit
Easy-Titer™ Human IgG (H+L) Assay Kit
Easy-Titer™ Human IgG (gamma chain) Assay Kit
Easy-Titer™ Human IgM Assay Kit

Pierce Plant Total Protein Extraction Kit (Thermo Scientific™)

The Thermo Scientific Pierce Plant Total Protein Extraction Kit effectively extracts protein from all kinds of dry and fresh plant tissue without liquid nitrogen or organic solvents.

Features of the Plant Total Protein Extraction Kit:
Efficient—obtain excellent protein yields in less than 10 minutes using a single buffer and a spin column
Versatile—native or denaturing lysis buffers for protein extraction from leaves, stems, and seeds
Compatible—extracts can be quantified using the BCA Protein Assay Kit or the Rapid Gold BCA Protein Assay Kit

The Pierce Plant Total Protein Extraction Kit is composed of optimized buffers and filter cartridges that allow for efficient and rapid protein extraction in less than 10 minutes. The kit is designed to rapidly extract denatured or native proteins from plant tissues (leaves, seeds, soft stem, roots, etc.). Simply grind the sample in the lysis buffer in the filter cartridge and centrifuge. The protein extracts can be used for applications such as SDS-PAGE, western blotting, immunoprecipitation, affinity purification, and activity assays.

Related products
Halt Protease & Phosphatase Inhibitor Cocktail
Halt Protease & Phosphatase Inhibitor Cocktail, EDTA-free (100X)
Pierce Rapid Gold BCA Protein Assay Kit
Pierce BCA Protein Assay Kit

Pierce™ Peroxide Assay Reagent A (Thermo Scientific™)

Thermo Scientific Pierce Peroxide Assay Reagent A is a formulation consisting of 25mM ammonium ferrous sulfate. This formulation is one of the component of Quantitative Peroxide Assay Kit used for detecting and measuring hydrogen peroxide levels based on the oxidation of ferrous to ferric ion in the presence of xylenol orange, present in the biological and other liquid samples.

Applications of Pierce Quantitative Peroxide Assay Kits:
• General hydrogen peroxide (H2O2) measurement in protein samples
• Quantitation of peroxides in detergents
• Assessment of the effects of peroxides on cellular activity
• Determination of protein glycation; Measurement of peroxide accumulation in lipids

In these assay kits, hydroperoxides convert the Fe2+ to Fe3+ at acidic pH. With the aqueous-compatible formulation, peroxide first reacts with sorbitol, converting it to a peroxyl radical, which in turn initiates Fe2+ oxidation to Fe3+. In the lipid compatible formulation, the peroxide converts the Fe2+ to Fe3+ directly. In a sulfuric acid solution, the Fe3+ complexes with the xylenol orange (XO) dye to yield a purple product having an absorbance maximum at 560nm. Peroxide levels in test samples can be determined by calculation from the know extinction coefficient of the XO-Fe complex or by reference to a standard curve prepared with hydrogen peroxide solution.Most proteins do not interfere with these assays, although some metal chelators may require use of a blank (i.e., control) to mitigate these effects.


Related Products
Pierce™ Quantitative Peroxide Assay Kit (Aqueous)
Pierce™ Quantitative Peroxide Assay Kit (Lipid)
Pierce™ Peroxide Assay Reagent B
Pierce™ Peroxide Assay Reagent C

Pro-Detect™ Rapid MBP Assay Kit (Thermo Scientific™)

The Thermo Scientific Pro-Detect Rapid MBP Assay Kit is a single-use, dipstick lateral flow kit for quick, easy detection of maltose binding protein (MBP)-tagged proteins in protein expression and purification systems. This lateral flow assay uses membrane-based strips coated with dye-bound conjugated antibodies specific to the MBP tag to provide a visual, color readout for detection within ten minutes. This assay can be used to detect MBP-tagged proteins directly from cell culture media (supernatant) or cell lysates without any special instrumentation or handling.

Features of the Pro-Detect Rapid assay kits:
Easy to adopt—lateral flow strips can be used early in and throughout expression to monitor and confirm expression of desired protein-tagged target
Simple, fast method—simply dilute sample using provided diluent and dip in the lateral flow strip for visual results within 5-10 minutes
Sensitive—detect protein tags in supernatant or cell lysate samples down to low µg/mL concentrations
Specific—assay does not cross-react with common lysis and protein preparation reagents
Reliable—results are similar to other antibody immunoassays, including western blot and ELISA
Long shelf life—stable for at least one year at 4°C

Each Pro-Detect Rapid assay is performed by simply adding a properly diluted tissue culture supernatant, lysate, or purified protein sample to a test tube or microplate well and dipping in a lateral flow strip. Gold-conjugated detection antibodies embedded in the strip form complexes with the tagged protein in the sample. These complexes travel the length of the strip membrane and bind at the test and control lines. Results are displayed as red bands.

Pro-Detect™ Rapid Mouse Fc Assay Kit (Thermo Scientific™)

The Thermo Scientific Pro-Detect Rapid Mouse Fc Assay Kit is a single-use, dipstick lateral flow kit for quick, easy detection of mouse Fc-tagged proteins in protein expression and purification systems. This lateral flow assay uses membrane-based strips coated with dye-bound conjugated antibodies specific to the mouse Fc tag to provide a visual, color readout for detection within ten minutes. This assay can be used to detect mouse Fc-tagged proteins directly from cell culture media (supernatant) or cell lysates without any special instrumentation or handling.

Features of the Pro-Detect Rapid assay kits:
Easy to adopt—lateral flow strips can be used early in and throughout expression to monitor and confirm expression of desired protein-tagged target
Simple, fast method—simply dilute sample using provided diluent and dip in the lateral flow strip for visual results within 5-10 minutes
Sensitive—detect protein tags in supernatant or cell lysate samples down to low µg/mL concentrations
Specific—assay does not cross-react with common lysis and protein preparation reagents
Reliable—results are similar to other antibody immunoassays, including western blot and ELISA
Long shelf life—stable for at least one year at 4°C

Each Pro-Detect Rapid assay is performed by simply adding a properly diluted tissue culture supernatant, lysate, or purified protein sample to a test tube or microplate well and dipping in a lateral flow strip. Gold-conjugated detection antibodies embedded in the strip form complexes with the tagged protein in the sample. These complexes travel the length of the strip membrane and bind at the test and control lines. Results are displayed as red bands.

Pro-Detect™ Rapid HA Competitive Assay Kit (Thermo Scientific™)

The Thermo Scientific Pro-Detect Rapid HA Competitive Assay Kit is a single-use, dipstick lateral flow kit for quick, easy detection of human influenza hemagglutinin (HA)-tagged proteins in protein expression and purification systems. This lateral flow assay uses membrane-based strips coated with dye-bound conjugated antibodies specific to HA tag to provide a qualitative detection within ten minutes. This assay can be used to detect HA-tagged proteins directly from cell culture media (supernatant) or cell lysates without any special instrumentation or handling.

Features of the Pro-Detect Rapid competitive assay kits:
Easy to adopt—lateral flow strips can be used early in and throughout expression to monitor and confirm expression of desired protein-tagged target
Simple, fast method—simply dilute sample using provided diluent and dip in the lateral flow strip for qualitative results within 5-10 minutes
Sensitive—detect protein tags in supernatant or cell lysate samples down to low µg/mL concentrations
Specific—assay does not cross-react with common lysis and protein preparation reagents
Reliable—results are similar to other antibody immunoassays, including western blot and ELISA
Long shelf life—stable for at least one year at 4°C

Each Pro-Detect Rapid competitive assay is performed by simply adding a properly diluted tissue culture supernatant, lysate, or purified protein sample to a test tube or microplate well and dipping in a lateral flow strip. Gold-conjugated detection antibodies embedded in the strip form complexes with the tagged protein in the sample. In the presence of target protein tag, the dye-bound conjugated antibodies will bind to the tagged protein present in the sample instead of the protein tag bound at the test lines. Therefore, in a positive result, a competitive lateral flow assay will show decreasing intensity of the visible test lines until all test lines have disappeared. When there is no target protein tag present, the dye-bound conjugated antibodies specific to the target will bind at the test line(s), resulting in visual test lines in a negative result.

Rapid ELISA Mouse mAb Isotyping Kit (Thermo Scientific™)

The Thermo Scientific Pierce Rapid ELISA Mouse mAb Isotyping Kit provides antigen-independent determination of mouse monoclonal antibody isotype using a microplate method that enables multiple samples to be tested in about one hour.

Features of the Rapid ELISA Mouse mAb Isotyping Kit:

Fast—determine antibody isotype in approx. 1 hour; considerably faster than traditional ELISA kits
Convenient—eight-well strip format allows partial use of the plate; use one strip (column) for each sample (12 samples per plate)
Specific—characterize antibodies for six different subclasses and two different light-chain types
Sensitive—accurate characterization with samples containing at least 3 ng/mL of test antibody
Flexible—kit is compatible with hybridoma cell culture supernatant, ascites fluid or purified antibodies
Cost effective—cost per assay is less than with single-use assay strips or cassettes
No special equipment needed—assess results visually or measure quantitatively using an ordinary ELISA plate reader (450nm)
Complete and easy to use—includes precoated plates, detecting antibody, buffers, and TMB substrate and stop solutions

This fast assay uses ELISA strip-plates that are pre-coated in different wells with anti-mouse heavy-chain capture antibodies (anti-IgG1, IgG2a, IgG2b, IgG3, IgA and IgM) or anti-mouse light-chain capture antibody (kappa or lambda). This approach eliminates the need to purify and immobilize an antigen to determine immunoglobulin isotype (antibody subclass and light chain identity). A mouse monoclonal antibody sample applied to the wells can be isotyped within one hour. Results are evaluated qualitatively by visual inspection or quantitatively by measuring the absorbance at 450nm.

Related Products
Pierce™ Rapid Antibody Isotyping Kit - Mouse
Pierce™ Rapid Antibody Isotyping Kit plus Kappa and Lambda - Mouse

Pro-Detect™ Rapid Antibody Isotyping Assay Kit, mouse (Thermo Scientific™)

The Thermo Scientific Pro-Detect Rapid Antibody Isotyping Assay Kit - Mouse is a single-use, dipstick lateral flow kit for quick, easy determination of mouse monoclonal antibody class and subclass identity. This antibody isotyping assay uses membrane-based strips coated with dye-bound conjugated antibodies that provide a visual, color readout of the monoclonal antibody isotype within ten minutes. The kit determines mouse IgG1, IgG2a, IgG2b, IgG3, IgA, IgM, as well as light-chain identity (kappa vs. lambda light chains).

Features of the Pro-Detect Rapid Antibody Isotyping Assay Kit:
Long shelf life—stable for at least one year at 4°C
Simple workflow—dilute antibody sample using provided diluent and dip in the lateral flow strip
Fast—within 5–10 minutes a band appears that indicates the antibody isotype
Sensitive—detect antibodies in tissue culture media or ascites fluid samples down to low ng/mL concentrations
Specific—assay does not cross-react with fetal bovine serum (FBS)
Reliable—results are similar to standard ELISA-based isotyping assays

Each Pro-Detect Rapid Antibody Isotyping assay is performed by simply adding a properly diluted tissue culture supernatant or mouse ascites sample to a test tube or microplate well and dipping in a lateral flow strip. Gold conjugates embedded in the strip membrane form specific class- and subclass-soluble complexes with the antibodies in the sample. These complexes travel the length of the membrane and are resolved on the anti-isotype and class-specific antibody-impregnated regions of the membrane. Results are displayed as a red band above the printed class or sub-class description, indicating the antibody isotype present.

Determining the class and subclass of a monoclonal antibody is useful in planning the best immunoglobulin purification method. For example, mouse IgA and IgM are best purified by size (i.e., gel exclusion) or using immunoaffinity separation columns. Mouse IgG2a and IgG2b are purified with immobilized Protein A at pH 7–8, while mouse IgG1 binds best to Protein A at pH 8–9. Immunoglobulin that contains kappa light chains can be purified using immobilized Protein L.

The Pro-Detect Rapid Antibody Isotyping Assay Kit is compatible with both tissue culture supernatant and mouse ascites fluid, and is more sensitive than conventional latex bead-based dipstick assays and much faster than ELISA-based isotyping assays. The kit requires only 0.5 µL ascites fluid, 2–22 µL of cell culture supernatant or 1.5 ng of purified antibody.

EZQ™ Protein Quantitation Kit (Invitrogen™)

The EZQ Protein Quantitation Kit provides a fluorescence-based protein assay that facilitates fast quantitation of protein samples prepared for gel electrophoresis. The assay can be performed in the presence of detergents, urea and reducing agents—simply spot 1 µL of your protein sample onto the prepared paper, stain with our proprietary fluorescent dye, and measure the fluorescence. Samples can be quantitated by comparison with a standard curve. For added versatility, we provide a specially-designed 96-well microplate for easy quantitation of samples on a microplate reader or a laser scanner.

Pierce™ Biotinylated Protein Interaction Pull-Down Kit (Thermo Scientific™)

The Thermo Scientific Pierce Biotinylated Protein Interaction Pull-Down Kit contains the necessary components to capture and purify interactors of a biotin-labeled protein or ligand.

Features of the Biotinylated Protein Interaction Pull-Down Kit:

• Provides a complete, affordable and easy-to-use strategy for discoverying protein:protein interactions
• Uses common laboratory equipment and reagents (e.g., microcentrifuges, mini-gels, protein stains)
• Adaptable to single- or multiple-sample demands
• Flexible pull-down format uses spin cups for easy and efficient manipulation of streptavidin agarose beads

You provide the biotinylated protein as the "bait" (see

Related Products
EZ-Link™ Desthiobiotinylation and Pull-Down Kit

EZ-Link™ Desthiobiotinylation and Pull-Down Kit (Thermo Scientific™)

The Thermo Scientific EZ-Link Desthiobiotinylation and Pull-Down Kit is a complete set of reagents to biotin-label purified proteins and use them to purify interaction complexes using streptavidin agarose resin with mild elution conditions.

Features of the EZ-Link Desthiobiotinylation and Pull-Down Kit:

Sulfo-NHS-LC-Desthiobiotin – label proteins with a biotin-like that specifically binds streptavidin but also easily elutes with mild conditions
Pull-down assay – simple, optimized protocol and reagents to label proteins and recover (purify) intact, functional protein interaction complexes
Complete kit – includes labeling reagent and desalting columns to prepare bait-proteins, and streptavidin agarose and elution buffer to perform pull-down

This all-in-one labeling and purification kit uses Sulfo-NHS-LC-Desthiobiotin, an amine-reactive NHS-ester reagent, to effectively tag a purified or mixed protein sample for use as bait in capturing and purifying protein interactions. The desthiobiotin tags of labeled proteins bind to streptavidin with high specificity yet readily elute with very mild conditions (i.e., by competitive displacement with regular, free biotin). The system enables effective yet gentle capture and isolation (pull-down) of specific protein interaction complexes from cell lysates using streptavidin agarose beads. The complete kit includes ready-to-use 1 mg vials of desthiobiotinylation reagent, desalting columns to process labeled protein, and high-capacity streptavidin agarose with buffers to perform several microcentrifuge-scale pull-down assay experiments with ease. Identify novel interactions between a known protein (bait) and previously undiscovered target (prey), or confirm interactions among known bait and prey proteins.

Desthiobiotin is a single-ring, sulfur-free analog of biotin that binds to streptavidin with nearly equal specificity but less affinity than biotin (1/Kd = 1011 vs. 1015M, respectively). Consequently, desthiobiotinylated bait proteins and their interacting partners can be eluted readily and specifically from streptavidin affinity resin using mild conditions based on competitive displacement with free biotin. For pull-down assay experiments with biological samples, this soft-release characteristic of desthiobiotin also helps to minimize co-purification of endogenous biotinylated molecules, which remain bound to streptavidin upon elution of the target protein complexes with free biotin. The modified avidin-biotin affinity system also eliminates the need to use harsh elution conditions that might disassociate complexes and/or damage the target protein or cell. Desthiobiotin-based techniques are ideal when using native or recombinant proteins that are not expressed with a fusion tag and when isolating captured proteins under native conditions, such as targeting intact cells or cell surface proteins.

Sulfo-NHS-LC-Desthiobiotin is a variant of biotin that is activated as a sulfo-NHS ester with a long-chain (LC) spacer arm to covalently label primary amines (-NH2) of proteins or other molecules with desthiobiotin groups. The No-Weigh Format (1 mg resealable vials) eliminates the difficulties associated with weighing small quantities of reagent and maximizes protection of unused reagent from hydrolysis.

Related Products
Pierce™ Biotinylated Protein Interaction Pull-Down Kit

Pierce™ BCA Solid (Thermo Scientific™)

Thermo Scientific BCA (bicinchonic acid) is for use in BCA protein assays for the determination of protein concentration.

Related Products
Pierce™ BCA Protein Assay Kit
Pierce™ BCA Protein Assay Reagent A
Pierce™ BCA Protein Assay Reagent B

Compat-Able™ Protein Assay Preparation Reagent Kit (Thermo Scientific™)

The Thermo Scientific Compat-Able Protein Assay Preparation Set eliminates interfering substances from protein assay samples to make them compatible with BCA and Bradford assays.

The Compat-Able Reagents remove salts, detergents, reducing agents and other substances from protein samples to eliminate interference with protein assays. The protocol selectively precipitates all of the protein, thereby allowing the non-protein components to be easily decanted and removed. The purified, precipitated protein is redissolved in water, making it ready for accurate determination of the protein concentration by standard protein assay methods. The procedure is accomplished in less than 10 minutes with just a few simple steps. The Compat-Able Preparation Set is available individually or conveniently bundled with either the Thermo Scientific Pierce BCA Protein Assay Kit or the Thermo Scientific Pierce Coomassie Plus Protein Assay Kit.

Features of the Compat-Able Protein Assay Preparation Reagent Kit:

Eliminate incompatibilities—removes nearly any substance that interferes with colorimetric protein assays: salts, detergents, denaturants, reducing agents, and even IEF sample buffer
Simple and fast—prepare samples in less than 10 minutes with four simple steps
Convenient—reagent set is easier to use than homemade TCA or acetone precipitation reagents, thereby producing more consistent results
Scalable—microcentrifuge method is easily scaled to larger centrifuge tube volumes for special needs
Validated—tested and offered together with BCA and Coomassie Plus Protein Assay Kits; protocol integrates control and normalization procedures

Related Products
Compat-Able™ BCA Protein Assay Kit
Compat-Able™ Coomassie Plus Protein Assay Kit

Pierce™ BCA Protein Assay Kit - Reducing Agent Compatible (Thermo Scientific™)

This BCA Protein Assay Kit is the reducing agent-compatible version of our popular Thermo Scientific Pierce BCA Protein Assay. The kit enables you to measure protein concentration in samples that contain thiol-reductants dithiothreitol (DTT) and 2-mercaptoethanol (BME).

Features of the BCA Protein Assay Kit—Reducing Agent Compatible:

Compatible—assay samples that contain up to 5 mM DTT, 35 mM BME, or 10 mM TCEP
BCA technology—only a slight modification of the standard BCA Protein Assay protocol (15-minute incubation with Compatibility Reagent); no precipitation steps required
Small samples—requires only 25 µL (standard kit) or less than 10 µL (microplate kit) of sample
Colorimetric—measure with a standard spectrophotometer or plate reader (562nm)
Excellent uniformity—exhibits less protein-to-protein variation than dye-binding methods
High linearity—linear working range for BSA equals 125 to 2000 µg/mL

The BCA Protein Assay Kit—Reducing Agent Compatible (BCA-RAC) provides all of the advantages of the original BCA Assay, plus compatibility with disulfide reducing agents at concentrations routinely used in protein sample buffers. This special adaptation of the popular Pierce BCA Protein Assay method enables accurate protein concentration measurement for samples containing DTT, 2-ME or TCEP. This reducing agent compatible (RAC) BCA Kit extends the already broad reagent compatibility of the BCA Protein Assay protocol to include nearly all types of components commonly present in protein research samples.

Related Products
Pierce™ Microplate BCA Protein Assay Kit - Reducing Agent Compatible
96-Well Plates for Pierce™ BCA-RAC Assay

Glycoprotein Standards Set for Pierce™ Glycoprotein Carbohydrate Estimation Kit (Thermo Scientific™)

The Thermo Scientific Pierce Glycoprotein Standards Set includes six purified standards (two negative and four positive controls) intended for use with any glycoprotein carbohydrate determination protocol.

Related Products
Pierce™ Glycoprotein Carbohydrate Estimation Kit