Shop All Labels & Labeling Kits

Zenon™ Alexa Fluor™ 532 Rabbit IgG Labeling Kit (Invitrogen™)

Zenon® labeling technology provides a fast, versatile, and reliable method for adding a fluorescent label to an antibody. You need only a small amount of starting material, and the method is optimized for efficient labeling of antibodies in serum, ascites fluid, or hybridoma suspensions. Antibody conjugates formed using Zenon® technology may be used in any protocol where a directly labeled primary antibody is suitable, including flow cytometry, imaging, and high-throughput applications. This exclusive Molecular Probes® Zenon® labeling technology greatly simplifies the use of multiple mouse-derived antibodies in the same staining protocol.

Important Features of Zenon® Labeling Technology:

• Labeled antibodies typically ready to use in 10 minutes
• Requires only 1–20 μg primary antibody
• Simple, no purification required
• Flexible–over 24 fluorophores plus biotin, HRP, alkaline phosphatase, and TSA to choose from
• Multiplex with other mouse monoclonal antibodies simultaneously


Save Time and Antibody
Each kit comes with affinity-purified monovalent Fab fragment of a goat anti-Fc antibody (or, in the case of the Zenon® Goat IgG Labeling Kits, a rabbit anti-Fc antibody) that has been conjugated to one of our premier Alexa Fluor® dyes or to Pacific Blue™, Pacific Orange™, fluorescein, or Texas Red®-X dyes, biotin R-phycoerythrin (R-PE), allophycocyanin (APC), HRP, or alkaline phosphatase.

Formation of the Fab–antibody complex with the Zenon® Antibody Labeling Kits is extremely fast (5 min for complex, 5 min for blocking step). And Zenon® labeling is a reliable and reproducible method, even with as low 0.4 μg in 2 μL of primary antibody. There is minimal waste of expensive or difficult-to-obtain antibodies when using the Zenon® Antibody Labeling Kits.

Preserve Primary Antibody Function and Affinities
Reactive dye labeling of primary antibodies can have unpredictable and undesirable outcomes. Among these are reduced binding affinities by label addition in the binding pocket. Zenon® antibody labeling approach, targeted to the Fc tail, avoids this concern.

Moreover the Zenon® dye- and enzyme-labeled Fab fragments have been affinity purified during their preparation to help ensure their high affinity and selectivity for the Fc portion of the corresponding primary antibody. The procedure for chemical labeling of the Fab fragments protects the Fc-binding site, resulting in more active labeling reagents.

Many Fluorophore and Enzyme Labels Available
Zenon® immunolabeling technology makes it very easy to change fluorescent color combinations or detection methodologies by simply using a different dye- or enzyme-labeled Fab fragment from our extensive selection of over 100 Zenon® Antibody Labeling Kits. If larger quantities or covalent attachment of the label is desired, see Antibody Labeling from A to Z or use our Labeling Chemistry Selection Tool for other choices.

Zenon® Technology Simplifies the Use of Multiple Antibodies of the Same Isotype in the Same Protocol
The stability of the Zenon® complex is sufficient to allow sequential (or simultaneous) labeling of different targets in cells and tissues with multiple antibody complexes. Subsequent to staining, an aldehyde-based fixation step can permanently block the transfer of Zenon® labels between different primary antibodies and will preserve the staining pattern.

We’ll Make a Custom Antibody Conjugate for You
If you can’t find what you’re looking for in our stocked list, we’ll prepare a custom antibody conjugate for you. Our custom conjugation service is efficient and confidential, and we stand by the quality of our work. We are ISO 9001:2000 certified.

For Research Use Only. Not intended for animal or human therapeutic or diagnostic use.

Related Links:

Zenon® Labeling Technology
Zenon® Technology: Versatile Reagents for Immunolabeling—Section 7.3

GlcNAz (N-azidoacetylglucosamine tetraacylated) (Thermo Scientific™)

Thermo Scientific Pierce GlcNAz (N-azidoacetylglucosamine-tetraacylated) is an azide-labeled sugar that provides a highly specific approach for studying glycoproteins through in vivo metabolic labeling and chemoselective ligation.

Features of Azido-Sugars:

Bioorthogonal—the azido group is small, nonreactive and absent from living systems; as such the azido-sugar compounds do not interfere with endogenous cellular pathways and substitute for their naturally occurring analogs
Compatible—reaction chemistry with phosphine compounds occurs effectively in simple buffer conditions; requires no accessory reagents such as copper or reducing agents
Chemoselective—azide and phosphine groups do not react or interfere with components of biological samples but conjugate to one another with high efficiency
Versatile—azide tag can be targeted for detection, immobilization, conjugation or affinity purification depending on which phosphine-activated compound it is reacted with

These sugars are azide-derivatives of naturally occurring monosaccharides that cells use to glycosylate proteins using post-translational modification biochemical pathways. The azide functional group is small and nonreactive with endogenous molecules. When supplied to cells, these compounds become incorporated by glycosylation events to effectively "tag" glycoproteins with the azide group. The azide group then can be specifically targeted for detection or conjugation using alkyne-activated reagents ("click" chemistry) or phosphine-activated reagents (Staudinger ligation).

When used in combination with phosphine-activated fluorescent dyes, biotin reagents, and or other compounds, these azido-modified sugars facilitate the investigation of cellular pathways involving glycosylation.

There are several classes of glycoproteins grouped by the type of carbohydrate and amino acid linkage site. N-linked glycosylation is a modification of asparagine amines, whereas O-linked glycosylation occurs through the hydroxyl of serine and threonine residues. The azido-modified sugars are metabolic substitutes for endogenous amino sugars. ManNAz is converted by cells to an azido sialic acid derivative that is used for N-linked glycosylation of cell surface proteins. GlcNAz and GalNAz are predominantly used to label the O-linked glycosylation (O-GlcNAc and O-GalNAc).

Related Products
ManNAz (N-azidoacetylmannosamine tetraacylated)
GalNAz (N-azidoacetylgalactosamine tetraacylated)

DyLight™ 680 NHS Ester (Thermo Scientific™)

Thermo Scientific DyLight 680 Amine-Reactive Dye is an NHS ester-activated derivative of high-performance DyLight 680 used to fluorescently label antibodies and other proteins that are then used as molecular probes for cellular imaging and other fluorescence detection methods.

DyLight 680 produces near-infrared (IR) fluorescence that replaces other near-IR dyes, including Cy5.5™ dye and Alexa Fluor™ 680, and is ideal for multi-color applications. The high water solubility of DyLight Fluors means that a high dye-to-protein ratio can be attained without causing precipitation of the conjugates. DyLight 680 Amine-Reactive Dye is also available as part of two antibody labeling kit sizes.

Features of DyLight 680 NHS-Ester:

High performance—DyLight 680 fluoresces brighter than Alexa Fluor 680 and Cy5.5 dye
Specific—NHS ester-activated dye labels proteins and other molecules at primary amines (-NH2)
Optimized procedure—following the standard protocol results in antibodies with excellent dye:protein ratios and recovery rates for optimum activity and fluorescence labeling

Applications:
• Primary antibody labeling for immunofluorescence microscopy, immunohistochemistry (IHC), Western blotting, or ELISA assay
• Target protein labeling for in vitro and in vivo fluorescent detection strategies

DyLight 680 Amine-Reactive Dye is activated with an N-hydroxysuccinimide (NHS) ester moiety to react with exposed N-terminal α-amino groups or the ε-amino groups of lysine residues to form stable amide bonds. Learn more about NHS ester chemistry.

Typical labeling reactions require the dye to first be dissolved in anhydrous dimethyl formamide (DMF) or another suitable organic solvent before adding a specific molar amount of dye to an amine-free buffer containing the protein to be labeled. However, the high solubility of DyLight Fluors permits protein solutions to be added directly to specific amounts of the labeling reagent. This feature allows DyLight 680 Amine-Reactive Dye to be provided in multiple formats with flexible protocols to achieve efficient degrees of labeling.

We also offer Standard and Microscale DyLight 680 Antibody Labeling Kits for fast and efficient fluorescent labeling of antibodies for use in fluorescence methods.The standard size kit contains all necessary components to perform three separate labeling reactions using 1 mg of IgG or similar quantities of other proteins. The microscale kit contains all of the necessary components to perform five separate labeling reactions using 100 µg of IgG. Both kit sizes include the Amine-Reactive DyLight 680 NHS-ester in convenient single-use vials as well as purification resin and spin columns for the preparation of ready-to-use conjugate.

Related Products
DyLight™ 680 Antibody Labeling Kit
DyLight™ 680 Microscale Antibody Labeling Kit

Alexa Fluor™ 514 NHS Ester (Succinimidyl Ester) (Invitrogen™)

Alexa Fluor® 514 is a bright, green-fluorescent dye. Used for stable signal generation in imaging and flow cytometry, Alexa Fluor® 514 dye is water soluble and pH-insensitive from pH 4 to pH 10. In addition to reactive dye formulations, we offer Alexa Fluor® 514 dye conjugated to a variety of antibodies, peptides, proteins, tracers, and amplification substrates optimized for cellular labeling and detection.

The NHS ester (or succinimidyl ester) of Alexa Fluor® 514 is the most popular tool for conjugating this dye to a protein or antibody. NHS esters can be used to label to the primary amines (R-NH2) of proteins, amine-modified oligonucleotides, and other amine-containing molecules. The resulting Alexa Fluor® conjugate will exhibit brighter fluorescence and greater photostability than the conjugates of other spectrally similar fluorophores.

Detailed information about this AlexaFluor® NHS ester:

Fluorophore label: Alexa Fluor® 514 dye
Reactive group: NHS ester
Reactivity: Primary amines on proteins and ligands, amine-modified oligonucleotides
Ex/Em of the conjugate: 517/542 nm
Extinction coefficient: 80,000 cm-1M-2

Typical Conjugation Reaction
You can conjugate amine-reactive reagents with virtually any protein or peptide (the provided protocol is optimized for IgG antibodies). You can scale the reaction for any amount of protein, but the concentration of the protein should be at least 2 mg/mL for optimal results. We recommend trying three different degrees of labeling, using three different molar ratios of the reactive reagent to protein.

The Alexa Fluor® NHS ester is typically dissolved in high-quality anhydrous dimethylformamide (DMF) or dimethylsulfoxide (DMSO) (D12345), and the reaction is carried out in 0.1–0.2 M sodium bicarbonate buffer, pH 8.3, at room temperature for 1 hour. Because the pKa of the terminal amine is lower than that of the lysine epsilon-amino group, you may achieve more selective labeling of the amine terminus using a buffer closer to neutral pH.

Conjugate Purification
Labeled antibodies are typically separated from free Alexa Fluor® dye using a gel filtration column, such as Sephadex™ G-25, BioGel® P-30, or equivalent. For much larger or smaller proteins, select a gel filtration media with an appropriate molecular weight cut-off or purify by dialysis. We offer several purification kits optimized for different quantities of antibody conjugate:
Antibody Conjugate Purification Kit for 0.5-1 mg (A33086)
Antibody Conjugate Purification Kit for 20-50 µg (A33087)
Antibody Conjugate Purification kit for 50-100 µg (A33088)

Learn More About Protein and Antibody Labeling
We offer a wide selection of Molecular Probes® antibody and protein labeling kits to fit your starting material and your experimental setup. See our Antibody Labeling kits or use our Labeling Chemistry Selection Tool for other choices. To learn more about our labeling kits, read Kits for Labeling Proteins and Nucleic Acids—Section 1.2 in The Molecular Probes® Handbook.

We’ll Make a Custom Conjugate for You
If you can’t find what you’re looking for in our online catalog, we’ll prepare a custom antibody or protein conjugate for you. Our custom conjugation service is efficient and confidential, and we stand by the quality of our work. We are ISO 9001:2000 certified.

Zenon™ Alexa Fluor™ 594 Mouse IgG2a Labeling Kit (Invitrogen™)

Zenon® labeling technology provides a fast, versatile, and reliable method for adding a fluorescent label to an antibody. You need only a small amount of starting material, and the method is optimized for efficient labeling of antibodies in serum, ascites fluid, or hybridoma suspensions. Antibody conjugates formed using Zenon® technology may be used in any protocol where a directly labeled primary antibody is suitable, including flow cytometry, imaging, and high-throughput applications. This exclusive Molecular Probes® Zenon® labeling technology greatly simplifies the use of multiple mouse-derived antibodies in the same staining protocol.

Important Features of Zenon® Labeling Technology:

• Labeled antibodies typically ready to use in 10 minutes
• Requires only 1–20 μg primary antibody
• Simple, no purification required
• Flexible–over 24 fluorophores plus biotin, HRP, alkaline phosphatase, and TSA to choose from
• Multiplex with other mouse monoclonal antibodies simultaneously


Save Time and Antibody
Each kit comes with affinity-purified monovalent Fab fragment of a goat anti-Fc antibody (or, in the case of the Zenon® Goat IgG Labeling Kits, a rabbit anti-Fc antibody) that has been conjugated to one of our premier Alexa Fluor® dyes or to Pacific Blue™, Pacific Orange™, fluorescein, or Texas Red®-X dyes, biotin R-phycoerythrin (R-PE), allophycocyanin (APC), HRP, or alkaline phosphatase.

Formation of the Fab–antibody complex with the Zenon® Antibody Labeling Kits is extremely fast (5 min for complex, 5 min for blocking step). And Zenon® labeling is a reliable and reproducible method, even with as low 0.4 μg in 2 μL of primary antibody. There is minimal waste of expensive or difficult-to-obtain antibodies when using the Zenon® Antibody Labeling Kits.

Preserve Primary Antibody Function and Affinities
Reactive dye labeling of primary antibodies can have unpredictable and undesirable outcomes. Among these are reduced binding affinities by label addition in the binding pocket. Zenon® antibody labeling approach, targeted to the Fc tail, avoids this concern.

Moreover the Zenon® dye- and enzyme-labeled Fab fragments have been affinity purified during their preparation to help ensure their high affinity and selectivity for the Fc portion of the corresponding primary antibody. The procedure for chemical labeling of the Fab fragments protects the Fc-binding site, resulting in more active labeling reagents.

Many Fluorophore and Enzyme Labels Available
Zenon® immunolabeling technology makes it very easy to change fluorescent color combinations or detection methodologies by simply using a different dye- or enzyme-labeled Fab fragment from our extensive selection of over 100 Zenon® Antibody Labeling Kits. If larger quantities or covalent attachment of the label is desired, see Antibody Labeling from A to Z or use our Labeling Chemistry Selection Tool for other choices.

Zenon® Technology Simplifies the Use of Multiple Antibodies of the Same Isotype in the Same Protocol
The stability of the Zenon® complex is sufficient to allow sequential (or simultaneous) labeling of different targets in cells and tissues with multiple antibody complexes. Subsequent to staining, an aldehyde-based fixation step can permanently block the transfer of Zenon® labels between different primary antibodies and will preserve the staining pattern.

We’ll Make a Custom Antibody Conjugate for You
If you can’t find what you’re looking for in our stocked list, we’ll prepare a custom antibody conjugate for you. Our custom conjugation service is efficient and confidential, and we stand by the quality of our work. We are ISO 9001:2000 certified.

For Research Use Only. Not intended for animal or human therapeutic or diagnostic use.

Related Links:

Zenon® Labeling Technology
Zenon® Technology: Versatile Reagents for Immunolabeling—Section 7.3

Qtracker™ 655 Cell Labeling Kit (Invitrogen™)

The reagents in the Qtracker® 655 Cell Labeling Kit use a custom targeting peptide to deliver red-fluorescent Qdot® 655 nanocrystals into the cytoplasm of live cells. Qtracker® Cell Labeling Kits are designed for loading cells grown in culture with highly fluorescent Qdot® nanocrystals. Once inside the cells, Qtracker® labels provide intense, stable fluorescence that can be traced through several generations, and are not transferred to adjacent cells in a population.

Need a different emission spectrum or longer tracking? View our other mammalian cell tracking products.

Key Attributes:

Qtracker® 655 label has Ex/Em (405-615/655) nm
Designed for loading cells grown in culture with highly fluorescent Qdot® nanocrystals
Provide intense, stable fluorescence that can be traced through several generations
Available in eight colors—525 nm, 565 nm, 585 nm, 605 nm, 625 nm, 655 nm, 705 nm, or 800 nm emission
Excellent tools for long-term tracking or imaging studies of live cells, including migration, motility, morphology, and other cell function assays

The Qtracker® Cell Labeling Kits use a custom targeting peptide to deliver Qdot® nanocrystals into the cytoplasm of live cells. Cytoplasmic delivery by this mechanism is not mediated by a specific enzyme; therefore, no cell-type specificity has been observed. Delivery is typically accomplished in less than 1 hour.

Qdot® nanocrystals delivered by the Qtracker® Cell Labeling Kits are compatible with serum-sensitive cells; intense fluorescence is maintained in complex cellular environments and under various biological conditions including changes in intracellular pH, temperature, and metabolic activity. Furthermore, autofluorescence commonly observed in cells or tissues can be avoided using Qtracker® 655, 705, or 800 Kits.

Long-Lasting, Targeted Signal
Using Qtracker® Cell Labeling Kits, you can observe labeled cells using extensive continuous illumination, without the photobleaching and degradation problems often associated with organic dyes. Qtracker® labels are distributed in vesicles in the cytoplasm, and are inherited by daughter cells for at least six generations. Fluorescence from the Qtracker® labels can be seen up to a week after delivery in some cell lines. Long-term cellular retention makes Qtracker® Cell Labeling Kits ideal for studying cell motility, migration, differentiation, morphology, and many other cellular function studies. Qtracker® labels do not leak out of intact cells to be taken up by adjacent cells in the population.

Monitor the Signal on Multiple Platforms
Qtracker® reagent-labeled live cells can be easily monitored on a variety of platforms, including flow cytometry, fluorescence/confocal microscopy, fluorescence microplate readers, and high-content imaging systems.

Minimal Impact on Live Cells
The cytotoxicity of the materials use in Qtracker® Cell Labeling Kits has been tested in a variety of cell lines including CHO, HeLa, U-118, 3T3, HUVEC, and Jurkat cells. Labeling with Qtracker® Cell Labeling Kits appears to exert minimal impact on cellular surface marker expression, cell proliferation, cellular enzyme activity, and cell motility.

Useful in a Variety of Cell Tracing Studies
Post-labeling, researchers have demonstrated a wide variety of applications for Qtracker® labeled cells, including cell co-culture and cell assembly into heterotypic assemblies, multilineage differentiation, trans-differentiation versus cell fusion, embryonic and mesenchymal stem cell tracking, and cell migration dynamics.

Click-IT™ AHA (L-Azidohomoalanine) (Invitrogen™)

Click-iT® AHA (L-azidohomoalaine) provides a fast, sensitive, non-toxic and most importantly non-radioactive alternative to the traditional radioactive technique, 35S-methionine for the detection of nascent protein. AHA is an amino acid analog that contains a very small modification, specifically an azido moiety that can be fed to cultured cells and incorporated into proteins during active protein synthesis. Detection utilizes the chemoselective ligation or “click " reaction between an azide and an alkyne where the azido modified protein is detected with one of the Click-iT® Protein Analysis Detection Kits containing either TAMRA, Dapoxyl®, or biotin alkyne. Detection sensitivity with these reagents in 1-D gels and Western blots is in the low femtomole range and compatible with downstream LC-MS⁄MS and MALDI MS analysis or Multiplexed Proteomics® reagents for differential analyses of newly synthesized proteins together with total glycoproteins, total phosphoproteins or total protein.

pHrodo™ iFL Red Microscale Protein Labeling Kit (Invitrogen™)

The pHrodo iFL Red Microscale Protein Labeling Kit provides the reagents needed to easily label 3 microscale purified protein or antibody samples (20–100 µg) with pHrodo iFL Red dye.

The pHrodo iFL Red Microscale Labeling Kit is:
Convenient—labeling typically takes 2 hours with less than 30 min hands-on time
Versatile—label proteins with molecular weights between 12 and 150 kDa
Customizable—create your own probes for studying antibody internalization, phagocytosis, and endocytosis

This kit contains amine-reactive pH-sensitive pHrodo iFL Red STP ester dye that covalently binds to free lysines anywhere they occur in an antibody or protein. pHrodo iFL Red dye is an improved version of pHrodoRed dye optimized for the creation of bright and soluble bioconjugates to be used in the study of antibody internalization, endocytosis, and phagocytosis. It is more soluble than the original pHrodo Red dye, making it useful for the labeling of antibodies that may otherwise precipitate out of solution during conjugation. pHrodo iFL Red dye dramatically increases fluorescence as the pH of its surroundings become more acidic. It is non-fluorescent outside the cell, but fluoresces bright red in phagosomes and endosomes.

Qdot™ 585 ITK™ Carboxyl Quantum Dots (Invitrogen™)

Qdot® 585 ITK™ carboxyl quantum dots are the ideal starting material for preparing custom conjugates that require high loading of biomolecules. These materials are carboxylate functionalized and can be coupled to amine groups of proteins and modified oligonucleotides using EDC-mediated condensation. The coatings of these probes provides more binding sites than our Qdot® ITK™ amino quantum dots, but lacks PEG linkers that help to prevent non-specific interactions. These materials can be conjugated to X-PEG-amine bi-functional linkers for custom reactivity and higher specificity. Our Qdot® ITK™ carboxyl quantum dots are provided as 8 µM solutions and are available in all 9 Qdot® probe colors.

Important Features of Qdot® ITK™ Carboxyl Quantum Dots:
• Qdot® 585 ITK™ carboxyl quantum dot has emission maxima of ~585 nm
• Extremely photostable and bright fluorescence
• Efficiently excited with single-line excitation sources
• Narrow emission, large Stokes shift
• Available in multiple colors
• Ideal labeling and tracking applications


Properties of Qdot® Nanocrystals
Qdot® probes are ideal for imaging and labeling applications that require bright fluorescent signals and/or real-time tracking. Unique among fluorescent reagents, all nine available colors of Qdot® probes can be simultaneously excited with a single (UV to blue-green) light source. This property makes these reagents excellent for economical and user-friendly multiplexing applications. Qdot® labels are based on semiconductor nanotechnology and are similar in scale to moderately sized proteins.

About the Innovator’s Tool Kit Qdot® ITK™ Reagents
These Qdot® ITK™ probes are ideal for researchers who wish to prepare specific (non-stocked) conjugates for their applications and need customizable conjugation functionality.

Other Forms of Qdot® Nanocrystals are Available
In addition to the carboxyl-derivatized form, we offer Qdot® ITK™ quantum dots with amino and aliphatic hydrocarbon modifications. We’ve also developed a wide range of Qdot® nanocrystals conjugates and labeling kits. Investigate the properties of Qdot® nanocrystals or read the Molecular Probes® Handbook Section 6.6—Qdot® Nanocrystals to find out more.

For Research Use Only. Not intended for any animal or human therapeutic or diagnostic use.

Click-IT™ GalNAz Metabolic Glycoprotein Labeling Reagent (Tetraacetylated N-Azidoacetylgalactosamine) (Invitrogen™)

The Click-iT® GalNAz metabolic glycoprotein labeling reagent provides the first part of a simple and robust two-step technique to identify and characterize cell surface O-linked glycoproteins. In step one, cultured cells are incubated with the azide-modified galactosamine (GalNAz). The azido-sugar is metabolically incorporated into cell surface O-linked glycoproteins through the permissive nature of the oligosaccharide biosynthesis pathway. In step two, via the chemoselective ligation or click reaction between an azide and an alkyne, the azido-labeled glycoproteins can then be detected with a Click-iT® Glycoprotein Detection Kit for gels (TAMRA or Dapoxyl® alkyne) or Western blots (biotin alkyne). These Click-iT® products are compatible with LC-MS⁄MS and Multiplexed Proteomics™ technologies for in-depth analyses of the glycoproteome.

EZ-Link™ HPDP-Biotin, No-Weigh™ Format (Thermo Scientific™)

Thermo Scientific EZ-Link HPDP-Biotin is a membrane-permeable biotin labeling reagent that reacts with sulfhydryl (-SH) groups. The resulting disulfide bond between the target sulfhydryl molecule and the biotin group can be cleaved by reducing agents to release the biotin group and regenerate the protein (or peptide) in its original, unmodified form. Labeling with HPDP-Biotin is convenient when using immobilized avidin, streptavidin, or Thermo Scientific NeutrAvidin Protein to purify the target molecules for reducing SDS PAGE or mass analysis; the captured biotinylated molecules can be efficiently eluted from the support by cleaving the disulfide bond with dithiothreitol (DTT) or other reducing agent rather than by attempting to dissociate the high affinity interaction between avidin and biotin with strong acid or denaturant.

Thermo Scientific No-Weigh products are specialty reagents provided in a pre-aliquoted format. The pre-weighed packaging prevents the loss of reagent reactivity and contamination over time by eliminating the repetitive opening and closing of the vial. The format enables use of a fresh vial of reagent each time, eliminating the hassle of weighing small amounts of reagents and reducing concerns over reagent stability.

Features of EZ-Link HPDP-Biotin:

Protein labeling—biotinylate antibodies or other proteins for use in protein methods
Thiol-reactive—reacts with sulfhydryls (-SH), such as the side-chain of cysteine (C)
Pyridyldithiol-activated—perform reactions at pH 6.5 to 7.5 in buffers such as PBS
Reversible—forms disulfide bonds, which can be cleaved using DTT or other reducing agent
Solubility—must be dissolved in DMSO or DMF before further dilution in aqueous buffers
Medium length—spacer arm (total length added to target) is 29.2 angstroms

HPDP-Biotin is a pyridyldithiol-biotin compound for labeling protein cysteines and other molecules that contain sulfhydryl groups. This reagent specifically reacts with reduced thiols (-SH) in near-neutral buffers to form reversible disulfide bonds. HPDP-Biotin is useful for labeling and affinity-purification applications that require recovery of the original, unmodified molecule. For example, a protein can be biotinylated, allowed to bind its interactor, then captured to a streptavidin column and finally eluted and recovered by reduction of the disulfide bond with dithiothreitol.

We manufacture biotin reagents to ensure the highest possible overall product integrity, consistency and performance for the intended research applications.

Biotinylation reagents differ in reactivity, length, solubility, cell permeability and cleavability. Three types of sulfhydryl-reactive compounds are available: maleimido, iodoacetyl and pyridyldithiol. Pyridyldithiol reagents specifically react with sulfhydryl groups (-SH) in near-neutral buffers to form reversible disulfide bonds.

In proteins, sulfhydryls exist where there are cysteine (C) residues. Cystine disulfide bonds must be reduced to make sulfhydryl groups available for labeling. Hinge-region disulfide bridges of antibodies can be selectively reduced to make functional half-antibodies that can be labeled.

Applications:
• Retrieve cell surface receptors and cleave the biotin away on an immobilized avidin column

HABA (4'-hydroxyazobenzene-2-carboxylic acid) (Thermo Scientific™)

Thermo Scientific Pierce HABA is 4'-hydroxyazobenzene-2-carboxylic acid, a simple reagent that enables spectrophotometric (colorimetric) estimation of biotinylation levels of labeled proteins and other molecules.

Features of HABA:

• HABA-avidin complex can be used over a wide range of pH and salt concentrations
• Amount of Avidin can be calculated directly from the increased absorbance at 500nm complexing with the HABA Dye
• Calculate results directly from absorbance values based on extinction coefficients using the procedure outlined in the instructions
• Complete kits also available! See Pierce Biotin Quantitation Kit (Part No. 28005) and Fluorescence Biotin Quantitation Kit (Part No. 46610)

Determine the molar ratio of biotin incorporated into a protein using the HABA-Avidin method. HABA dye (4'-hydroxyazobenzene-2-carboxylic acid ) binds to avidin to produce a yellow-orange colored complex which absorbs at 500nm. Free biotin will displace the HABA dye and cause the absorbance to decrease. A standard curve can be established using the free biotin to estimate the number of moles of biotin incorporated after biotinylating a protein. View online HABA Calculator.

Alexa Fluor™ 680 Protein Labeling Kit (Invitrogen™)

Molecular Probes® Protein Labeling Kits provide a convenient means for attaching a fluorescent label (or biotin) to an antibody (or a protein larger than 40 kDa). Conjugates are ideal for multiple applications, including flow cytometry, fluorescent microscopy, immunohistochemistry, primary detection, ELISAs, immunocytochemistry, FISH, and more. Kits are available in 12 Alexa Fluor® dye colors, biotin, the hapten Oregon Green® 488, fluorescein EX, and Texas Red® dye. Each kit provides the components needed to perform three protein conjugations and purifications.

Important Features of Protein Labeling Kits:

• Labeled proteins typically ready to use in 2 hr (~30 min hands-on time)
• Designed to label 1 mg of IgG
• Simple protocol—react, separate, use
• Stabilizing proteins must be removed from the sample before labeling


The Benefits of Alexa Fluor® Dyes
Compared to traditional dyes, Alexa Fluor® dyes are brighter, more photostable, and more pH resistant between pH 4 and 10. And generally when using Alexa Fluor® dyes, higher degrees of labeling can be achieved without intramolecular quenching. For details see Alexa Fluor® Dyes Spanning the Visible and Infrared Spectrum—Section 1.3.

Learn More About Protein and Antibody Labeling
We offer a wide selection of Molecular Probes® antibody and protein labeling kits to fit your starting material and your experimental setup. See Antibody Labeling from A to Z or use our Labeling Chemistry Selection Tool for other choices. To learn more about our various kits read Kits for Labeling Proteins and Nucleic Acids—Section 1.2 in the Molecular Probes® Handbook.

We’ll Make a Custom Antibody Conjugate for You
If you can’t find what you’re looking for in our stocked list, we’ll prepare a custom antibody conjugate for you. Our custom conjugation service is efficient and confidential, and we stand by the quality of our work. We are ISO 9001:2000 certified.

For Research Use Only. Not intended for animal or human therapeutic or diagnostic use.

Biotin Azide (PEG4 carboxamide-6-Azidohexanyl Biotin) (Invitrogen™)

The hapten, biotin azide is reactive with terminal alkynes via a copper-catalyzed click reaction. Biotin can be subsequently detected with streptavidin, avidin or NeutrAvidin® biotin-binding protein.

FITC (5/6-fluorescein isothiocyanate), mixed isomer (Thermo Scientific™)

Fluorescein isothiocyanate (FITC) is an amine-reactive derivative of fluorescein dye that has wide-ranging applications as a label for antibodies and other probes, for use in fluorescence microscopy, flow cytometry and immunofluorescence-based assays such as Western blotting and ELISA. The isothiocyanate variety of fluorescein efficiently labels antibodies and other purified proteins at primary amines (lysine side chains)

Properties of FITC:

• Alternative names: 5/6-FITC
• Chemical name: 5(6)-fluorescein isothiocyanate mixed isomer
• Molecular weight: 389.2
• Excitation source: 488 nm spectral line, argon-ion laser
• Excitation wavelength: 494 nm
• Emission wavelength: 518 nm
• Extinction coefficient: > 70,000 M-1cm-1
• CAS #: 27072-45-3
• Purity: > 95% by HPLC
• Solubility: Soluble in aqueous buffers at pH > 6
• Reactive groups: Isothiocyanate, reacts with primary amines at pH 7.0 to 9.0

Applications
• Label antibodies for use as immunofluorescent probes
• Label oligonucleotides for hybridization probes
• Detect proteins in gels and on Western blots

Related Products
NHS-Fluorescein (5/6-carboxyfluorescein succinimidyl ester), mixed isomer
Pierce™ NHS-Fluorescein Antibody Labeling Kit
Pierce™ FITC Antibody Labeling Kit