Shop All Protein Labeling Kits

Biotin-XX Microscale Protein Labeling Kit Invitrogen™

Microscale Protein Labeling Kits provide a convenient means for attaching a fluorescent label to a small amount of antibody or protein (20–100 µg). The kits are available in four Alexa Fluor® colors (or biotin) and supply everything needed for three labeling and separation reactions.

Important Features of Microscale Protein Labeling Kits:

• Labeled proteins typically ready to use typically in 2 hours (~30 minutes hands-on time)
• Optimized for 20–100 µg of protein with molecular weights between 12 and 150 kDa
• Purified using convenient spin filters with yields between 60 and 90%
• Stabilizing proteins must be removed from the sample before labeling


Stable Reaction Chemistry and Superior Alexa Fluor® Dyes
In this Microscale Protein Labeling Kit, the reactive label contains a succinimidyl (NHS) ester moiety that reacts with primary amines of proteins to form stable dye-protein conjugates. 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.

Pierce™ Biotin Quantitation Kit Thermo Scientific™

Thermo Scientific Pierce Biotin Quantitation Kit includes aliquots of HABA reagent and biotinylated protein standard for convenient colorimetric determination of biotinylation levels in labeled antibodies and other proteins.

Features of the Biotin Quantitation Kit:

Colorimetric – requires a plate reader or spectrophotometer set to measure at 500nm
Reliable – proven, well-characterized method for determination of biotinylation levels
Convenient – kit provides the essential reagents and standards to perform the assay with ease
Flexible – adaptable to spectrophotometer cuvettes or standard plate readers with 96-well microplates
Options – calculate results directly from absorbance values based on extinction coefficients using the procedure outlined in the instructions
Robust – supplied HABA-avidin complex can be used over a wide range of pH and salt concentrations

HABA dye (4'-hydroxyazobenzene-2-carboxylic acid) is a reagent that enables quick estimation of the mole-to-mole ratio of biotin to protein in a solution. The Pierce Biotin Quantitation Kit contains a premix of HABA and avidin and a biotinylated horseradish peroxidase (HRP) positive control. The HABA-Avidin Premix is supplied in convenient Thermo Scientific No-Weigh Microtube packaging, which eliminates the difficulties associated with weighing small quantities of reagent.

To quantitate biotinylation, a solution containing the biotinylated protein is added to a mixture of HABA and avidin. Because of its higher affinity for avidin, biotin displaces the HABA and the absorbance at 500nm decreases proportionately. By this method, an unknown amount of biotin present in a solution can be quantitated in a single cuvette by measuring the absorbance of the HABA-avidin solution before and after addition of the biotin-containing sample. The change in absorbance relates to the amount of biotin in the sample by the extinction coefficient of the HABA-avidin complex. View online HABA Calculator.

Pacific Blue™ Protein Labeling Kit Invitrogen™

*From start to finish, it takes less than three hours to label a protein and purify the resulting conjugate using the Pacific Blue™ Protein Labeling Kit. Although optimized for 1 mg of an IgG antibody, this kit can be used to make conjugates of other proteins larger than ~40,000 daltons. The kit provides sufficient material to perform three protein conjugations and purifications. To label 100 µg of an IgG, we have the Pacific Blue™ Monoclonal Antibody Labeling Kit P30013. Alternatively, the reactive dye provided in both of these kits is available separately P10163.

FluoReporter™ Mini-Biotin-XX Protein Labeling Kit Invitrogen™

The FluoReporter® Mini-biotin-XX Protein Labeling Kit provides a convenient and flexible means for attaching biotin-XX to your antibody or protein (>30 kDa). This kit contains a water-soluble biotin-XX sulfosuccinimidyl ester, where "XX" is a 14-atom spacer that separates the reactive ester from the biotin moiety, making the biotin more accessible to avidin or streptavidin. The kit supplies the reagents needed for 5 to 10 labeling and separation reactions.

Important Features of FluoReporter® Protein Labeling Kits:
• Labeled proteins typically ready to use in under 3 hours with very little hands-on time
• Optimized for 0.1–0.6 mg of protein with molecular weight >30 kDa
• Labeled proteins are purified using convenient spin filters
• Requires the antibody or protein be purified prior to labeling


Learn More About Protein Labeling
We offer a wide selection of Molecular Probes® protein and antibody 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 Labeled Protein for You
If you can’t find what you’re looking for in our stocked list, we’ll prepare a custom labeled protein for you. Our custom services are 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 human or animal therapeutic or diagnostic use.

pHrodo™ Red Microscale Labeling Kit Invitrogen™

pHrodo® Red is the new name for pHrodo®, a fluorogenic dye that dramatically increases in fluorescence as the pH of its surroundings become more acidic. Original pHrodo® and pHrodo® Red dyes are the same molecule. Use this pHrodo® Red microscale protein labeling kits to conveniently label 3 separate samples of small amounts (20-100 µg) of purified protein or antibody with pHrodo®-SE conjugate.

pHrodo® Red dye conjugates are non-fluorescent outside the cell, but fluoresce bright red in phagosomes, making them ideal tools for studies ranging from phagocytosis of bioparticles to receptor internalization. pHrodo Red™ offers staining that is faster and more accurate than ratiometric dyes.

The pHrodo® Red Microscale Labeling Kit Is:
Convenient—Labeling typically takes 2 hours with less than 30 min hands-on
Versatile—Label proteins with MW between 12 and 150 kDa
Customizable—Create your own probes for studying phagocytosis and endocytosis

Get Better Results in Endocytosis Studies
Endocytosis and phagocytosis underly physiological events ranging from host-pathogen response to receptor desensitization via internalization (as is common in the GPCR class of receptors). Once internalized, material can be acidified in endosomes or lysosomes. When conjugated to target molecules, our pHrodo® Red dye fluorogenic pH sensitive probe allows direct visual monitoring of material entering these acidic compartments. At neutral and basic pH values, pHrodo® Red dye emission is at its minimum; with acidification, pHrodo® Red dye emission is increased by as much as 8-fold (at pH 4). The fluorescence of pHrodo® Red dye is dimmed by complete media and whole blood, further improving the signal-to-noise ratio. The pHrodo® Red Microscale Labeling Kit can label proteins with molecular weights between 12 and 150 kDa, including IgG antibodies (~150 kDa) in quantities ranging from 20-100 µg.

Gain Experimental Flexibility with a Validated Technology
pHrodo® has been cited in over 150 publications and used in a variety of applications. It is validated in flow cytometry, high throughput and high content screening (HTS and HCS), and other imaging applications. pHrodo® Red offers reduced signal variability and improved timing compared to ratiometric dyes like BCECF and SNARF, and the lack of fluorescence outside the cell eliminates the need for wash steps and quencher dyes. The red fluorescence of pHrodo® Red is ideal for multiplexing applications with green-fluorescent compounds such GFP, Fluo-4, or calcein.

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

SAIVI™ Alexa Fluor™ 647 Antibody/Protein 1 mg-Labeling Kit Invitrogen™

The SAIVI Alexa Fluor® 647 Antibody/Protein 1 mg-Labeling Kit provides a convenient means to label proteins with Alexa Fluor® 647 near-IR emitting dye. The kit is optimized for labeling and purifying 1 mg of IgG per conjugation reaction; comparable amounts of other proteins (>30 kDa) can also be labeled. To conveniently control the degree of labeling (DOL), this kit includes a DOL modulating reagent and instructions for decreasing the DOL from its intrinsic highest value. Using this method, protein preparations with varying ratios of dye to protein can be quickly and reproducibly obtained, allowing more efficient optimization in applications such as in vivo imaging, where the DOL of a protein can have significant effects on the signal-to-background ratio, biodistribution, and clearance.

Alexa Fluor™ 555 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.

Alexa Fluor™ 647 Microscale Protein Labeling Kit Invitrogen™

Microscale Protein Labeling Kits provide a convenient means for attaching a fluorescent label to a small amount of antibody or protein (20–100 µg). The kits are available in four Alexa Fluor® colors (or biotin) and supply everything needed for three labeling and separation reactions.

Important Features of Microscale Protein Labeling Kits:
• Labeled proteins typically ready to use typically in 2 hours (~30 minutes hands-on time)
• Optimized for 20–100 µg of protein with molecular weights between 12 and 150 kDa
• Purified using convenient spin filters with yields between 60 and 90%
• Stabilizing proteins must be removed from the sample before labeling

Stable Reaction Chemistry and Superior Alexa Fluor® Dyes
In the Microscale Protein Labeling Kits, the reactive dye contains a succinimidyl (NHS) ester moiety that reacts with primary amines of proteins to form stable dye-protein conjugates. 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.

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.

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.

EZ-Link™ Sulfo NHS-SS Biotinylation Kit Thermo Scientific™

The Thermo Scientific EZ-Link Sulfo NHS-SS Biotinylation Kit contains sufficient reagents for 10 biotinylation reactions (e.g., 1–10 mg antibody per reaction). The EZ-Link Sulfo-NHS-SS-Biotin included in the kit is a water-soluble, NHS-ester biotinylation reagent whose spacer arm includes a cleavable disulfide bond for reversible labeling of proteins and cell surface primary amines.

Features of EZ-Link Sulfo-NHS-SS-Biotin:

Protein labeling – biotinylate antibodies to facilitate immobilization, purification or detection
Cell surface labeling – biotinylates only surface proteins of whole cells because the negatively charged reagent does not permeate cell membranes
Amine-reactive—reacts with primary amines (-NH2), such as lysine side-chains, or the amino-termini of polypeptides
Cleavable—disulfide bond in spacer arm allows the biotin label to be removed using reducing agents such as DTT; only a small sulfhydryl group remains attached to the molecule
Soluble – charged sulfo-NHS group increases reagent water solubility compared to ordinary NHS-ester compounds
Medium length—spacer arm (total length added to target) is 24.3 angstroms; it consists of the native biotin valeric acid group extended by a 7-atom chain

Sulfo-NHS-SS-Biotin is a thiol-cleavable amine-reactive biotinylation reagent that contains an extended spacer arm to reduce steric hindrances associated with avidin binding. This reagent is water-soluble, enabling biotinylation to be performed in the absence of organic solvents such as DMSO or DMF for applications that cannot tolerate solvents or are complicated by their inclusion. The compound is particularly useful for labeling and purifying cell surface proteins, because (a) its sulfonate group prevents it from permeating cell membranes and (b) its cleavable spacer arm enables initially biotinylated proteins to be released from streptavidin affinity columns.

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

N-Hydroxysulfosuccinimide (NHS) esters of biotin are the most popular type of biotinylation reagent. NHS-activated biotins react efficiently with primary amino groups (-NH2) in alkaline buffers to form stable amide bonds. Proteins (e.g., antibodies) typically have several primary amines that are available as targets for labeling, including the side chain of lysine (K) residues and the N-terminus of each polypeptide.

Varieties of biotin NHS-ester reagents differ in length, solubility, cell permeability and cleavability. Non-sulfonated NHS-biotins are cell permeable but must be dissolved in organic solvent such as DMSO or DMF. Sulfo-NHS biotins (and those with pegylated spacers) are directly water soluble but not membrane permeable. Varieties containing disulfide bonds can be cleaved using reducing agents, enabling the biotin group to be disconnected from the labeled protein.

Related Products
EZ-Link™ Sulfo-NHS-SS-Biotin
EZ-Link™ Micro Sulfo-NHS-SS-Biotinylation Kit

Oregon Green™ 488 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.

Click-IT™ Myristic Acid, Azide (12-Azidododecanoic Acid) Invitrogen™

Identify and characterize myristylated proteins with Click-iT® myristic acid, azide using the powerful click chemistry, a simple and robust two-step labeling and detection technique. In step one, the azide-containing biomolecule is fed to cells or animals and actively incorporated into proteins. Unlike other labels such as biotin or a fluorescent dye, the azide-tag is small enough that the tagged molecule is an acceptable substrate for the enzymes that incorporate this building block into proteins. Detection utilizes the chemoselective ligation or “click" reaction between and azide and an alkyne where the modified protein is detected with the corresponding alkyne-containing dye or hapten using either the Click-iT® Cell Reaction Buffer Kit or the Click-iT® Protein Buffer Kit. With the Click-iT® Cell Reaction Buffer Kit, cells can be analyzed by fluorescence microscopy, flow cytometry or high-content imaging and analysis (HCS) together with other biomarkers of interest for content and context rich results. With the Click-iT® Protein Reaction Buffer Kit, achieve detection sensitivity in 1-D gels and western blots in the low femtomole range or perform LC-MS⁄MS and MALDI MS analysis.

Click-IT™ Tetramethylrhodamine (TAMRA) Protein Analysis Detection Kit Invitrogen™

The Click-iT® Tetramethylrhodamine (TAMRA) Glycoprotein Detection Kit provides the second part of the simple and robust two-step technique to identify and characterize glycoproteins by one- or two-dimensional gel electrophoresis. In step two, after the incorporation of the azide handle into protein glycan structures with either a Click-iT® metabolic labeling reagent or the Click-iT® Enzymatic Labeling system, the azide-modified glycoproteins are detected via the chemoselective ligation or click reaction between an azide and an alkyne. Gels with TAMRA labeled glycoproteins can be subsequently stained with the Multiplexed Proteomics™ technologies, SYPRO® Ruby total protein stain and PRO-Q® Emerald glycoprotein stain for the differential analysis of glycoprotein subclasses, total proteins and total glycoproteins in the same gel. Click-iT® modified glycoproteins are also compatible with downstream LC-MS/MS and MALDI MS analysis for identification.

Click-iT™ HPG Alexa Fluor™ 488 Protein Synthesis Assay Kit Invitrogen™

The Click-iT® HPG Alexa Fluor® 488 Protein Synthesis Assay Kit provides a fast, sensitive, non-toxic, and non-radioactive method for the detection of nascent protein synthesis utilizing fluorescence microscopy, high-content imaging, or flow cytometry. Included in the kit are L-homopropargylglycine (HPG), an amino acid analog of methionine containing an alkyne moiety, and Alexa Fluor® 488 azide. The HPG is fed to cultured cells and incorporated into proteins during active protein synthesis. Addition of the Alexa Fluor® 488 azide leads to a chemoselective ligation or 'click' reaction between the green fluorescent azide and the alkyne, allowing the modified proteins to be detected by imaged-based analysis.

Non-radioactive alternative—an alternative to the traditional 35S-methionine
Visualize bulk protein dynamics—fluorescent tagging of proteins allows their localization to be determined, including aggregation
Specificity—selective, specific reaction between label and detection tags
Stability —product contains an irreversible, covalent bond
Multiplex-enabled—use in conjuction with Click®-iT AHA (azide amino acid and alkyne dye) to detect spatial and temporal differences
Applicability to biological samples—easy detection; high sensitivity and low background, regardless of complexity

The Click-iT® HPG Alexa Fluor® 488 Protein Synthesis Assay Kit has been successfully tested in HeLa, A549, and U-2 OS cells with a variety of reagents that inhibit protein synthesis, including cycloheximide and anisomycin. The applicability of these probes to monitor protein degradation has also been shown using inhibitors of the proteasome (MG132 and Bortezomib) and blockers of autophagy (chloroquine) in HeLa cells.

Additionally, due to differences in Click-iT® chemistry between the Click-iT® HPG Alexa Fluor® 488 Protein Synthesis Assay Kit and Click®-iT AHA with Alexa Fluor® 594 Alkyne, these reagents can be used in conjunction for spatial or temporal determination of differences in nascent protein synthesis.
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