Shop All Labels & Labeling Kits

CellTrace™ Oregon Green™ 488 Carboxylic Acid Diacetate, Succinimidyl Ester (Carboxy-DFFDA, SE), cell permeant, mixed isomers (Invitrogen™)

Like CFDA SE, CellTrace™ Oregon Green® 488 (carboxy-DFFDA SE) should be a useful tool for following proliferating cells. This Oregon Green® 488 probe passively diffuses into cells, where it is colorless and nonfluorescent until its acetate groups are removed by intracellular esterases to yield a highly fluorescent, amine-reactive dye. Upon reaction with intracellular amines, the probe forms Oregon Green® 488 conjugates that are well-retained by cells. Unlike fluorescein conjugates, Oregon Green® 488 conjugates exhibit bright, photostable green fluorescence that is independent of pH at typical cellular pH values (pH-6-8).

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.

APEX™ Alexa Fluor™ 647 Antibody Labeling Kit (Invitrogen™)

The APEX® Antibody Labeling Kits are our best option for covalently attaching a fluorophore to small amounts of IgG antibody (~10–20 μg). It is ideal for the efficient labeling of antibodies in serum, ascites fluid, or hybridoma suspensions. Labeled antibodies are ready for use in imaging or flow cytometry applications in as little as 2.5 hours with very little hands on time.

Important Features of Alexa Fluor® APEX® Antibody Labeling Kits:

• Labeled antibodies typically ready to use in 2.5 hours (~15 minutes hands on time)
• Designed to label 10–20 μg of IgG
• Covalent attachment
• Compatible with contaminating proteins or stabilizers like BSA
• No columns needed; everything you need is supplied for 5 separate labelings
• Choose from Alexa Fluor® 488, 555, 568, 594, and 647 dyes, Oregon Green® 488 dye, Pacific Blue™ dye, and Biotin-XX.


Better Results and Workflows With Primary Labeled Antibodies
A primary antibody directly labeled with a fluorophore often produces lower background fluorescence and less nonspecific binding. Further, multiple primary antibodies of the same isotype or derived from the same species can easily be used in the same experiment if they are directly labeled with compatible fluorophores.

Contaminating Proteins or Protein Stabilizers Are Not a Problem
Many IgG antibodies are often available only in small quantities and packaged with stabilizing proteins, such as BSA, or other contaminants which can interfere with the amine-reactive labeling reagents. The APEX® Antibody Labeling Kits avoids this by utilizing a solid-phase labeling technique that captures the IgG antibody on the resin inside the APEX® antibody labeling tip. Contaminants are simply eluted through the tip, prior to applying the amine-reactive label.

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.

Measure-IT™ Thiol Assay Kit (Invitrogen™)

The Measure-iT™ Thiol Assay Kit proves easy and accurate quantitation of thiol. The assay has a linear range of 0.05-5 uM thiol, making it up to 400 times more sensitive than colorimetric methods based on Ellman's reagent. The assay is performed at room temperature; maximum fluorescence signal is attained in 5 minutes and is stable for at least 1 hour.

DyLight™ 633 Microscale Antibody Labeling Kit (Thermo Scientific™)

The Thermo Scientific DyLight 633 Microscale Antibody Labeling Kit contains an NHS ester-activated derivative of high-performance DyLight 633 used to fluorescently label antibodies and other proteins that are then used as molecular probes for cellular imaging and other fluorescence detection methods. The microscale kit contains all of the necessary components to perform five separate labeling reactions using 100 µg of IgG—the amine-reactive DyLight 633 NHS-ester in convenient single-use vials as well as purification resin and spin columns for the preparation of ready-to-use conjugate.

DyLight 633 fluoresces red and has physical properties comparable to other 633 dyes, including Alexa Fluor™ 633. 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 633 Amine-Reactive Dye is available as a stand-alone reagent.

Features of DyLight 633 NHS Ester:

High performance—DyLight 633 shows brighter fluorescence than Alexa Fluor 633
Specific—NHS ester-activated dye labels proteins and other molecules at primary amines (-NH2)
Convenient kit sizes—standard and microscale sizes are offered to match your experimental needs
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 633 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 DyLight 633 Amine-Reactive 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 633 Amine-Reactive Dye to be provided in multiple formats with flexible protocols to achieve efficient degrees of labeling.

Related Products
DyLight™ 633 NHS Ester
DyLight™ 633 Antibody Labeling Kit

4-Acetamido-4'-Maleimidylstilbene-2,2'-Disulfonic Acid, Disodium Salt (Invitrogen™)

Our 4-acetamido-4'-maleimidylstilbene-2,2'- disulfonic acid is a thiol-reactive reagent that is water soluble, with high polarity and membrane impermeability. This polysulfonated dye is useful for determining whether thiol-containing proteins and polypeptide chains are exposed at the extracellular or cytoplasmic membrane surface.

Alexa Fluor™ 647 C2 Maleimide (Invitrogen™)

Alexa Fluor® 647 is a bright, far-red fluorescent dye with excitation ideally suited for the 594 nm or 633 nm laser lines. Used for stable signal generation in imaging and flow cytometry, Alexa Fluor® 647 dye is water soluble and pH-insensitive from pH 4 to pH 10. In addition to reactive dye formulations, we offer Alexa Fluor® 647 dye conjugated to a variety of antibodies, peptides, proteins, tracers, and amplification substrates optimized for cellular labeling and detection (learn more).

The maleimide derivative of Alexa Fluor® 647 is the most popular tool for conjugating the dye to a thiol group on a protein, oligonucleotide thiophosphate, or low molecular weight ligand. The resulting Alexa Fluor® 647 conjugates exhibit brighter fluorescence and greater photostability than the conjugates of other spectrally similar fluorophores.

Detailed information about this AlexaFluor® maleimide:

Fluorophore label: Alexa Fluor® 647 dye
Reactive group: maleimide
Reactivity: thiol groups on proteins and ligands, oligonucleotide thiophosphates
Ex/Em of the conjugate: 651/671 nm
Extinction coefficient: 265,000 cm-1M-1
Spectrally similar dyes: Cy5
Molecular weight: ~1250

Typical Conjugation Reaction
The protein should be dissolved at a concentration of 50-100 µM in a suitable buffer (10-100 mM phosphate, Tris, or HEPES) at pH 7.0-7.5. In this pH range, the protein thiol groups are sufficiently nucleophilic that they react almost exclusively with the reagent in the presence of the more numerous protein amine groups, which are protonated and relatively unreactive. We recommend reducing any disulfide bonds at this point using a 10-fold molar excess of reducing agent such as DTT or TCEP. Excess DTT must be removed by dialysis and subsequent thiol-modification should be carried out under oxygen-free conditions to prevent reformation of the disulfide bonds; these precautions are not necessary when using TCEP prior to maleimide conjugation.

The Alexa Fluor® maleimide is typically dissolved in high-quality anhydrous dimethylsulfoxide (DMSO) at a concentration of 1-10 mM immediately prior to use, and stock solutions should be protected from light as much as possible. Generally, this stock solution is added to the protein solution dropwise while stirring to produce approximately 10-20 moles of reagent per mole of protein, and the reaction is allowed to proceed at room temperature for 2 hours or at 4°C overnight, protected from light. Any unreacted thiol-reactive reagent can be consumed by adding excess glutathione, mercaptoethanol, or other soluble low molecular weight thiol.

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.

5-IAF (5-iodoacetamido-fluorescein) (Thermo Scientific™)

Thermo Scientific 5-Iodoacetamido-Fluorescein (5-IAF) is a high-performance derivative of fluorescein dye, activated for easy and reliable labeling of antibodies, proteins and other molecules for use as fluorescent probes. 5-Iodoacetamido-Fluorescein is a sulfhydryl-reactive derivative of fluorescein that labels proteins and other molecules having free thiols (cysteine side chains)

Properties of 5-Iodoacetamido-Fluorescein:

• Alternative names: 5-IAF, 5-iodoacetamidofluorescein
• Chemical name: Acetamide, N-(3',6'-dihydroxy-3-oxospiro (isobenzofuran-1(3H), 9'-(9H)xanthen)-5-yl)-2-iodo
• Molecular weight: 515.26±3
• Excitation source: 488 nm spectral line, argon-ion laser
• Excitation wavelength: 494 nm
• Emission wavelength: 518 nm
• Extinction coefficient: > 80,000 M-1cm-1
• CAS #: 63368-54-7
• Solubility: Soluble in DMF; aqueous buffers at pH > 6
• Reactive groups: Iodoacetamide, reacts with sulfhydryls at pH 7.0 to 7.5

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

Related Products
Fluorescein-5-Maleimide

Alexa Fluor™ 532 Antibody Labeling Kit (Invitrogen™)

Molecular Probes® Alexa Fluor® Antibody Labeling Kits provide a convenient means to label small amounts of antibodies with Alexa Fluor® dyes (choice of 10 colors). This kit is optimized for labeling 100 µg of antibody per reaction with green-yellow fluorescent Alexa Fluor® 532. Comparably small amounts of other proteins (>40 kDa) can also be labeled.

The kit contains everything you need to perform five separate labeling reactions as well as to purify the resulting conjugates. Conjugates are ideal for multiple applications, including flow cytometry, fluorescent microscopy, immunohistochemistry, primary detection, ELISAs, immunocytochemistry, indirect FISH, and more.

Important Features of Alexa Fluor® 532 Antibody Labeling Kit:
• With an excitation and emission maximum of 530/554 nm, Alexa Fluor® 532 can be efficiently excited using a 532 nm Nd:YAG laser line and detected under standard Rhodamine 6G filters
• Labeled proteins typically ready to use typically in 90 min (~15 min hands-on time)
• Useful for labeling 100 µg of protein
• Optimized for small-scale labeling of any protein >40 kDa
• Purified using convenient spin filters
• Stabilizing proteins must be removed from the sample before labeling
• Includes detailed instructions for determining degree of labeling (DOL)


Better Results and Workflows with Primary labeled antibodies
A primary antibody directly labeled with a fluorophore often produces lower background fluorescence and less nonspecific binding. Further, multiple primary antibodies of the same isotype or derived from the same species can easily be used in the same experiment if they are directly labeled with compatible fluorophores.

Superior 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 for use in diagnostic procedures.

DyLight™ 650-Phosphine (Thermo Scientific™)

Thermo Scientific DyLight Fluor Phosphine Reagents are phosphine-activated fluorescent dyes for specific labeling and detection of azide-tagged molecules, which enables use of fluorescence imaging in metabolic labeling strategies.

When used in combination with azide labeling strategies, phosphine-activated DyLight Fluors enable selective fluorescent labeling for detection of protein interactions and post-translational modifications using fluorescence imaging technologies. The phosphine group conjugates to azide groups by the Staudinger reaction mechanism. Azide groups can be introduced into proteins or other cellular targets through in vivo labeling with azide-tagged derivatives of naturally occurring metabolic building blocks. Because neither phosphines nor azides are present in biological systems, they comprise a chemoselective (mutually specific) ligation pair for labeling and conjugation.

General features of the phosphine-activated DyLight Fluors:

Soluble—easily dissolves in water-miscible solvents (e.g., DMSO) for subsequent dilution in aqueous reaction mixtures with cell lysates and other biological samples
Compatible—reaction chemistry occurs effectively in simple buffer conditions; requires no accessory reagents such as copper or reducing agents, and does not interfere with fluorescence applications
Chemoselective—the phosphine reactive group is specific in biological samples for bioorthogonal azide-tagged molecules, ensuring that fluorescent labeling is specific
High-performance fluorescence—DyLight 488, 550 and 650 are intense, highly stable fluorophores for green, orange and red fluorescent detection. (see DyLight Fluors)

Related Products
DyLight™ 488-Phosphine
DyLight™ 550-Phosphine

5(6)-FAM, SE (5-(and-6)-Carboxyfluorescein, Succinimidyl Ester), mixed isomers (Invitrogen™)

Searching for superior alternatives to fluorescein? Our Alexa Fluor Dye Series offers everything you're looking for and more.

Pierce™ Streptavidin, Maleimide-Activated (Thermo Scientific™)

Thermo Scientific Pierce Maleimide-Activated Streptavidin conjugate include streptavidin in a purified form, activated for crosslinking to sulfhydryl groups containing molecules.

Related Products
Pierce™ Streptavidin
Pierce™ Streptavidin, Horseradish Peroxidase Conjugated
Pierce™ Streptavidin, Alkaline Phosphatase Conjugated
Pierce™ Streptavidin, Hydrazide-Activated

Alexa Fluor™ 633 Hydrazide (Invitrogen™)

Alexa Fluor® 633 Hydrazide is useful as a cell tracer and as a reactive dye for labeling aldehydes or ketones in polysaccharides or glycoproteins. Alexa Fluor® 633 is a bright, far red fluorescent dye with excitation ideally suited to the 633 nm laser line. Used for stable signal generation in imaging and flow cytometry, Alexa Fluor® 633 dye is water soluble and pH-insensitive from pH 4 to pH 10.

Detailed information about this AlexaFluor® hydrazide:

• Fluorophore label : Alexa Fluor® 633 dye
• Reactive group: hydrazide
• Reactivity: Aldehydes or keytones in polysaccharides or glycoproteins
• Ex/Em of the conjugate: 624/643 nm
• Extinction coefficient: 110,000 cm-1M-1
• Spectrally similar dyes: Cy5
• Molecular weight: ~1,150

Cell Tracking and Tracing Applications
Alexa Fluor® hydrazides and hydroxlamines are useful as low molecular weight, membrane-impermeant, aldehyde-fixable cell tracers, exhibiting brighter fluorescence and greater photostability than cell tracers derived from other spectrally similar fluorophores. They are easily loaded into cells by microinjection, infusion from patch pipette, or uptake induced by our Influx™ Pinocytic Cell-Loading Reagent. Learn more about cell tracking and tracing.

Glycoprotein and Polysaccharide Labeling Applications
The Alexa Fluor® hydrazides and hydroxlamines are reactive molecules that can be used to add a fluorescent label to biomolecules containing aldehydes or ketones. Aldehydes and ketones can be introduced into polysaccharides and glycoproteins by periodate-mediated oxidation of vicinal diols. Galactose oxidase can also be used to oxidize terminal galactose residues of glycoproteins to aldehydes.

Hydrazide vs Hydroxylamine
Hydrazine derivatives react with ketones and aldehydes to yield relatively stable hydrazones. Hydroxylamine derivatives (aminooxy compounds) react with aldehydes and ketones to yield oximes. Oximes are superior to hydrazones with respect to hydrolytic stability. Both hydrazones and oximes can be reduced with sodium borohydride (NaBH4) to further increase the stability of the linkage.

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.

Related Products
DMSO (dimethylsulfoxide) (D12345)
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)

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

DyLight™ 755-4xPEG Maleimide (Thermo Scientific™)

Thermo Scientific DyLight 755-4xPEG Sulfhydryl-Reactive Dye is a maleimide-activated derivative of our high-performance DyLight 755 Dye used to fluorescently label cysteine-containing peptides, proteins or other biomolecular probes.

The DyLight 755-4xPEG dye contains 4 polyethylene glycol (PEG) chains that are non-cytotoxic, enhance fluorescence and reduce nonspecific binding of conjugates made with them. Conjugates made with DyLight 755-4xPEG Dye can be used as molecular probes for cellular imaging and other fluorescence detection methods. The NIR fluorescence properties of DyLight 755-4xPEG Dye make it especially useful in a variety of biological, chemical, and pharmaceutical applications, including in vivo imaging. The PEG chains also improve solubility of the dyes and labeled molecules in aqueous solution, aid in cell permeability and improve tissue retention.

Features of DyLight 755-4xPEG Maleimide:

High fluorescence intensity—significantly brighter fluorescence than Alexa Fluor™ 750
PEGylated—improves solubility in aqueous solution and aids in cell permeability
Specific—maleimide-activated dye labels proteins and other molecules at reduced sulfhydryls (-SH)

Applications:
• Fluorescence microscopy
In vivo or ex vivo imaging
• Cell-based assays
• Flow cytometry/fluorescence-activated cell sorting (FACS)

DyLight 755-4xPEG Sulfhydryl-Reactive Dye is activated with a maleic acid imide (maleimide) moiety to form a reactive alkylation reagent. Labeling occurs through reaction of the maleimide-activated dye with reduced sulfhydryl groups (-SH) to form stable thioether bonds. Maleimides are specific for sulfhydryl groups between pH 6.5-7.5. Learn more about maleimide chemistry.

Zenon™ Alexa Fluor™ 568 Mouse IgG1 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

Alexa Fluor™ 350 Hydrazide (Invitrogen™)

Alexa Fluor® 350 Hydrazide is useful as a cell tracer and as a reactive dye for labeling aldehydes or ketones in polysaccharides or glycoproteins. Alexa Fluor® 350 is a blue fluorescent dye with excitation ideally suited to the UV laser line. Used for stable signal generation in imaging and flow cytometry, Alexa Fluor® 350 dye is water soluble and pH-insensitive from pH 4 to pH 10. In addition to reactive dye formulations, we offer Alexa Fluor® 350 dye conjugated to a variety of antibodies, peptides, proteins, tracers, and amplification substrates optimized for cellular labeling and detection (learn more).

Detailed information about this AlexaFluor® hydrazide:

• Fluorophore label : Alexa Fluor® 350 dye
• Reactive group: hydrazide
• Reactivity: Aldehydes or keytones in polysaccharides or glycoproteins
• Ex/Em of the conjugate: 345/445 nm
• Extinction coefficient: 13,000 cm-1M-1
• Spectrally similar dyes: DAPI
• Molecular weight: 349.29

Cell Tracking and Tracing Applications
Alexa Fluor® hydrazides and hydroxlamines are useful as low molecular weight, membrane-impermeant, aldehyde-fixable cell tracers, exhibiting brighter fluorescence and greater photostability than cell tracers derived from other spectrally similar fluorophores. They are easily loaded into cells by microinjection, infusion from patch pipette, or uptake induced by our Influx™ Pinocytic Cell-Loading Reagent. Learn more about cell tracking and tracing.

Glycoprotein and Polysaccharide Labeling Applications
The Alexa Fluor® hydrazides and hydroxlamines are reactive molecules that can be used to add a fluorescent label to biomolecules containing aldehydes or ketones. Aldehydes and ketones can be introduced into polysaccharides and glycoproteins by periodate-mediated oxidation of vicinal diols. Galactose oxidase can also be used to oxidize terminal galactose residues of glycoproteins to aldehydes.

Hydrazide vs Hydroxylamine
Hydrazine derivatives react with ketones and aldehydes to yield relatively stable hydrazones. Hydroxylamine derivatives (aminooxy compounds) react with aldehydes and ketones to yield oximes. Oximes are superior to hydrazones with respect to hydrolytic stability. Both hydrazones and oximes can be reduced with sodium borohydride (NaBH4) to further increase the stability of the linkage.

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.

Related Products
DMSO (dimethylsulfoxide) (D12345)
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)

CellTracker™ Green BODIPY™ Dye (Invitrogen™)

CellTracker™ Green BODIPY® (8-chloromethyl-4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-S-indacene) is a fluorescent dye well suited for monitoring cell movement or location. This dye is well retained, allowing for multigenerational tracking of cellular movements. And the green excitation/emission spectra are ideal for multiplexing with red fluorescent dyes and proteins.

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

• Easy to use—remove medium, add dye, incubate 30 minutes, and image cells
• Fluorescent signal retention of >72 hours (typically three to six generations)
• Green excitation/emission spectra (522/529 nm maxima) ideal for multiplexing
• Low cytotoxicity—does not affect viability or proliferation

CellTracker™ Green BODIPY® fluorescent dye has been designed to freely pass through cell membranes into cells, where it is transformed into cell membrane-impermeant reaction products. CellTracker™ Green BODIPY® dye is retained in living cells through several generations. The dye is transferred to daughter cells, but not adjacent cells in a population. CellTracker™ Green BODIPY® dye is designed to display fluorescence for at least 72 hours, and the dye exhibits ideal tracking properties: it is stable, nontoxic at working concentrations, well retained in cells, and brightly fluorescent at physiological pH. Additionally, the excitation and emission spectra of CellTracker™ Green BODIPY® dye are well separated from RFP (red fluorescent protein) spectra allowing for multiplexing.

DyLight™ 633-B2 NHS Ester (Thermo Scientific™)

Thermo Scientific DyLight 633-B2 NHS Ester is a benzopyrillium-based red-emitting specialty dye that can be used to label peptides, antibodies, and other proteins at primary amines. This dye has excitation and emission peaks at 637 and 657 nm, respectively (in ethanol) and an extinction coefficient of 200,000 M-1cm-1

General features of DyLight red-emitting specialty dyes:

Large selection—the largest family of dyes available for red-emitting fluorescence applications
NHS ester reactive group—allows immediate labeling of antibodies, proteins, peptides, and other amine-containing molecules through amide bond formation
Multiple solubility options—choose from hydrophilic to hydrophobic dyes to optimize the right dye label for the best performance in a given application

DyLight Red-emitting Dyes are a family of labeling agents that provide bright fluorescence detection for imaging. Dyes can be selected based upon their characteristic excitation and emission properties or relative hydrophilicity and hydrophobicity attributes. Dyes that contain a greater number of negatively charged sulfonates generally will have greater water solubility than dyes with fewer sulfonates. More hydrophobic dyes often provide better cell penetrating ability in vivo, while more hydrophilic dyes have less nonspecific binding potential. Each dye contains an amine-reactive NHS ester for simple modification of antibodies, proteins, peptides or other biomolecules through amide bond formation.

DyLight Red-emitting Dyes are a family of labeling agents that provide bright fluorescence detection for imaging. Dyes can be selected based upon their characteristic excitation and emission properties or relative hydrophilicity and hydrophobicity attributes. Dyes that contain a greater number of negatively charged sulfonates generally will have greater water solubility than dyes with fewer sulfonates. More hydrophobic dyes often provide better cell penetrating ability in vivo, while more hydrophilic dyes have less nonspecific binding potential. Each dye contains an amine-reactive NHS ester for simple modification of antibodies, proteins, peptides or other biomolecules through amide bond formation.

Criteria to consider when choosing a DyLight Red-emitting Specialty Dye
• Excitation and emission wavelengths—choose the best dye to match the excitation and emission capabilities of your instrument
• Water solubility—choose a dye based on its relative hydrophilicity, which directly correlates to the number of negatively-charged sulfonates it has on its core structure. More hydrophilic dyes are best at maintaining water solubility of a labeled antibody and limiting the nonspecific binding of the conjugate. More hydrophobic dyes often are best at penetrating tissues and cell membranes in vivo, meaning that dyes with fewer sulfonates may work best for some applications.
• DyLight dye selection—the broad selection of red-emitting dyes allows a number of candidate dyes to be tested in a given application for optimal performance.

Applications:
• Fluorescence imaging
• Confocal microscopy
• Flow cytometry
• Spectral fluorescence imaging
In vivo imaging
• Fluorescent western blotting
• Protein microarrays
• Antibody labeling
• Peptide labeling
• Fluorescence correlation spectroscopy
• Protein arrays
• Single molecule detection
• Nanoparticle conjugation
• Biotin/streptavidin conjugation

Related Products
DyLight™ 615-B1 NHS Ester
DyLight™ 633-B1 NHS Ester
DyLight™ 633-B3 NHS Ester
DyLight™ 635-B2 NHS Ester

Alexa Fluor™ 430 NHS Ester (Succinimidyl Ester) (Invitrogen™)

Alexa Fluor® 430 is a bright, green-fluorescent dye. Used for stable signal generation in imaging and flow cytometry, Alexa Fluor® 430 dye is water soluble and pH-insensitive from pH 4 to pH 10. In addition to reactive dye formulations, we offer Alexa Fluor® 430 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® 430 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® 430 dye
Reactive group: NHS ester
Reactivity: Primary amines on proteins and ligands, amine-modified oligonucleotides
Ex/Em of the conjugate: 430/545 nm
Extinction coefficient: 15,000 cm-1M-1
Molecular weight: 701.8

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.

Alexa Fluor™ 633 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.

Fluorescein Cadaverine; 5-((5-Aminopentyl)thioureidyl)Fluorescein, Dihydrobromide Salt (Invitrogen™)

The primary aliphatic amine of fluorescein cadaverine can be reversibly coupled to aldehydes and ketones to form a Schiff base - which can be reduced to a generate stable amine derivative by sodium borohydride (NaBH4) or sodium cyanoborohydride (NaCNH3). Carboxylic acids of proteins and other water-soluble biopolymers can be coupled to this molecule in aqueous solution using water-soluble carbodiimides such as EDAC (E2247).

DyLight™ 800 Maleimide (Thermo Scientific™)

Thermo Scientific DyLight 800 Sulfhydryl-Reactive Dye is a maleimide-activated derivative of high-performance DyLight 800 used to fluorescently label sulfhydryl-containing peptides, proteins and other biomolecular probes.

DyLight 800 is a near-IR fluor that is invisible to the naked eye but increases the staining options when using infrared imaging systems. DyLight 800 has spectral properties that are very similar to other near-IR dyes, including Alexa Fluor™ 790 and IRDye™ 800. The high water solubility of DyLight Fluors means that a high dye-to-protein ratio can be attained without causing precipitation of the conjugates.

Features of DyLight 800 Maleimide:

High performance—DyLight 800 replaces Alexa Fluor 800 and IRDye 800 for near-infrared staining
Specific—maleimide-activated dye labels proteins and other molecules at reduced sulfhydryls (-SH)
Efficient labeling methods—well-characterized chemistry and optimized protocols provide for reliable, high-quality labeling
Optimized antibody labeling procedure—complete protocol for IgG reduction and labeling and calculating the labeling efficiency

Applications:
• Antibody labeling for immunofluorescence applications, including immunocytochemistry (ICC), immunohistochemistry (IHC), Western blotting, and ELISA assay
• Target macromolecule labeling for in vitro and in vivo fluorescent detection strategies

DyLight 800 Sulfhydryl-Reactive Dye is activated with a maleic acid imide (maleimide) moiety to form a reactive alkylation reagent. Labeling occurs through reaction of the maleimide-activated dye with reduced sulfhydryl groups (-SH) to form stable thioether bonds. Maleimides are specific for sulfhydryl groups between pH 6.5-7.5. Learn more about maleimide chemistry.

CellVue™ NIR815 Cell Labeling Kit (Invitrogen™)

CellVue™ dyes are lipophilic dyes that can be used to label the cell membrane for the purpose of identifying and tracking labeled cells. Cell labeling is rapid and stable and can be combined with fluorescently labeled antibodies and other markers of cellular function for flow cytometric analysis and fluorescent microscopy. Mini CellVue™ Kits are supplied with one vial of dye stock (1 mM in ethanol) and one vial of labeling vehicle (Diluent C).

CellVue™ NIR815 is a near-infrared fluorescent cell labeling reagent. It is optimally excited at 786 nm and has a peak emission of 814 nm. CellVue™ NIR815 has been reported to be useful for short-term in vivo cell tracking studies using a Pearl™ Imager or Odyssey Infrared Imaging System (Li-COR Biosciences, Inc., Lincoln, NE).

Reported Application
Microscopy, Immunocytochemistry, Cell Labeling

Pacific Orange™ Antibody Labeling Kit (Invitrogen™)

Molecular Probes™ Antibody Labeling Kits provide a convenient means to label small amounts of antibodies with the violet light-excitable Pacific Orange™ or Pacific Blue™ dyes. This kit is optimized for labeling 100 µg of antibody per reaction. Comparably small amounts of other proteins (>40 kDa) can also be labeled.

View a selection guide for all Antibody Labeling Kits.

View the Fluorophore Selection Guide.

The kit contains everything you need to perform five separate labeling reactions as well as to purify the resulting conjugates. Conjugates are ideal for multiple applications, including flow cytometry, fluorescent microscopy, immunohistochemistry, primary detection, ELISAs, immunocytochemistry, indirect FISH, and more.

Important features of antibody labeling kits:
• Pacific Orange™ has an excitation and emission maximum of 400/551 nm
• Labeled proteins typically ready to use in 90 min (~15 min hands-on time)
• Useful for labeling 100 µg of protein
• Optimized for small-scale labeling of any protein >40 kDa
• Purified using convenient spin filters
• Stabilizing proteins must be removed from the sample before labeling
• Includes detailed instructions for determining degree of labeling (DOL)


Better results and workflows with primary labeled antibodies
A primary antibody directly labeled with a fluorophore often produces lower background fluorescence and less nonspecific binding. Further, multiple primary antibodies of the same isotype or derived from the same species can easily be used in the same experiment if they are directly labeled with compatible fluorophores.

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.

DyLight™ 550 NHS Ester (Thermo Scientific™)

Thermo Scientific DyLight 550 Amine-Reactive Dye is an NHS ester-activated derivative of high-performance DyLight 550 used to fluorescently label antibodies and other proteins that are then used as molecular probes for cellular imaging and other fluorescence detection methods.

DyLight 550 provides vibrant orange-to-red fluorescence with better performance than other rhodamine derivatives, including Alexa Fluor™ 555, TRITC, and Cy3™ dye for fluorescent 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 550 Amine-Reactive Dye is also available as part of two antibody labeling kit sizes.

Features of DyLight 550 NHS Ester:

High performance—DyLight 550 shows brighter fluorescence than Alexa Fluor 555, TRITC, and Cy3 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 550 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 DyLight 550 Amine-Reactive 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 550 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 550 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 550 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™ 550 Antibody Labeling Kit
DyLight™ 550 Microscale Antibody Labeling Kit

Zenon™ Alexa Fluor™ 568 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

Zenon™ R-Phycoerythrin Mouse IgG1 Labeling Kit (Invitrogen™)

Zenon labeling technology provides a fast, versatile and reliable method for producing antibody conjugates, even with very small (submicrogram) amounts of starting material. Antibody conjugates formed using Zenon technology may be used to stain cells in any protocol where a directly labeled primary antibody is suitable, including flow cytometry, imaging, high throughput and other applications. Moreover, this technology simplifies applications that previously were time consuming or not practical, such as the use of multiple mouse-derived antibodies in the same staining protocol.

View a selection guide for all Zenon™ antibody labeling kits and other antibody labeling products.

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.

Pierce™ Premium Grade Sulfo-NHS-LC-Biotin (Thermo Scientific™)

Thermo Scientific Pierce Premium Grade Sulfo-NHS-LC-Biotin is our highest quality formulation of this popular amine-reactive biotinylation reagent, specially characterized for applications where product integrity and risk minimization are paramount.

Features of Premium Grade Sulfo-NHS-LC-Biotin:

Sulfo-NHS-LC-Biotin—popular amine-reactive biotinylation reagent for antibody labeling
High quality—identity and purity confirmed by several tests, including quantitative NMR
Product integrity—enhanced level of testing and characterization compared to standard grade
Lot retention—ample supply of past lots retained to ensure future process testing
Change management—Change Control Notification (CCN) service
Consistent manufacture—batch-specific manufacturing documentation review

Compared to the standard grade product, Premium Grade Sulfo-NHS-LC-Biotin provides more clearly defined quality and product support by including (a) increased analytical testing and product characterization, (b) greater batch-specific information and quality assurance review, (c) extensive lot sample retention and (d) change control notification. Sulfo-NHS-LC-Biotin is an intermediate-length, water-soluble biotinylation reagent for labeling antibodies, proteins and other molecules that have primary amines. Specific labeling of cell surface proteins is another common application for these uniquely water-soluble and membrane impermeable reagents.

Related Products
EZ-Link™ Sulfo-NHS-LC-Biotin

TAMRA, SE; 5-(and-6)-Carboxytetramethylrhodamine, Succinimidyl Ester (5(6)-TAMRA, SE), mixed isomers (Invitrogen™)

Tetramethylrhodamine (TMR) is an important fluorophore for preparing protein conjugates. Under the name TAMRA, the carboxylic acid of TMR has also achieved prominence as a dye for oligonucleotide labeling and automated DNA sequencing applications. 5-(and-6)-carboxytetramethylrhodamine, succinimidyl ester is the amine-reactive, mixed isomer form of TAMRA. Single isomer forms of 5-TAMRA SE (Cat no. C-2211) and 6-TAMRA SE (Cat. no. C-6123) are also available.

1-pyrenebutanoic acid, succinimidyl ester (Invitrogen™)

The amine-reactive 1-pyrenebutanoic acid, succinimidyl ester can be used to create environment-sensitive bioconjugates with this unique fluorophore.

SAIVI™ Rapid Antibody Labeling Kit, Alexa Fluor™ 680 (Invitrogen™)

The Alexa Fluor® 680 SAIVI™ Antibody Labeling Kit provides a convenient means to label antibodies with an optimal degree of labeling for in vivo imaging applications (DOL; ~2) over a 6-fold antibody concentration range with no adjustments in reaction volume, dye concentration, or antibody concentration necessary. Using this procedure, optimally labeled antibodies are ready for applications that require azide-free reagents, such as live-cell imaging or direct injection into animals.

Alexa Fluor™ 350 C5 Maleimide (Invitrogen™)

Alexa Fluor® 350 is a blue fluorescent dye with moderate photostability and excitation that matches the 350 nm laser line. Used for stable signal generation in imaging and flow cytometry, Alexa Fluor® 350 dye is water soluble and pH-insensitive from pH 4 to pH 10. In addition to reactive dye formulations, we offer Alexa Fluor® 350 dye conjugated to a variety of antibodies, peptides, proteins, tracers, and amplification substrates optimized for cellular labeling and detection (learn more).

The maleimide derivative of Alexa Fluor® 350 is the most popular tool for conjugating the dye to a thiol group on a protein, oligonucleotide thiophosphate, or low molecular weight ligand. The resulting Alexa Fluor® 350 conjugates exhibit brighter fluorescence and greater photostability than the conjugates of other spectrally similar fluorophores.

Detailed information about this AlexaFluor® maleimide:

Fluorophore label: Alexa Fluor® 350 dye
Reactive group: maleimide
Reactivity: thiol groups on proteins and ligands, oligonucleotide thiophosphates
Ex/Em of the conjugate: 345/444 nm
Extinction coefficient: 17,000 cm-1M-1
Spectrally similar dyes: Marina Blue
Molecular weight: 578.68

Typical Conjugation Reaction
The protein should be dissolved at a concentration of 50-100 µM in a suitable buffer (10-100 mM phosphate, Tris, or HEPES) at pH 7.0-7.5. In this pH range, the protein thiol groups are sufficiently nucleophilic that they react almost exclusively with the reagent in the presence of the more numerous protein amine groups, which are protonated and relatively unreactive. We recommend reducing any disulfide bonds at this point using a 10-fold molar excess of reducing agent such as DTT or TCEP. Excess DTT must be removed by dialysis and subsequent thiol-modification should be carried out under oxygen-free conditions to prevent reformation of the disulfide bonds; these precautions are not necessary when using TCEP prior to maleimide conjugation.

The Alexa Fluor® maleimide is typically dissolved in high-quality anhydrous dimethylsulfoxide (DMSO) at a concentration of 1-10 mM immediately prior to use, and stock solutions should be protected from light as much as possible. Generally, this stock solution is added to the protein solution dropwise while stirring to produce approximately 10-20 moles of reagent per mole of protein, and the reaction is allowed to proceed at room temperature for 2 hours or at 4°C overnight, protected from light. Any unreacted thiol-reactive reagent can be consumed by adding excess glutathione, mercaptoethanol, or other soluble low molecular weight thiol.

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™ 647—R-Phycoerythrin Mouse IgG1 Labeling Kit (Invitrogen™)

Zenon labeling technology provides a fast, versatile and reliable method for producing antibody conjugates, even with very small (submicrogram) amounts of starting material. Antibody conjugates formed using Zenon technology may be used to stain cells in any protocol where a directly labeled primary antibody is suitable, including flow cytometry, imaging, high throughput and other applications. Moreover, this technology simplifies applications that previously were time consuming or not practical, such as the use of multiple mouse-derived antibodies in the same staining protocol.

View a selection guide for all Zenon™ antibody labeling kits and other antibody labeling products.

DyLight™ 650 Antibody Labeling Kit (Thermo Scientific™)

The Thermo Scientific DyLight 650 Antibody Labeling Kit contains an NHS ester-activated derivative of high-performance DyLight 650 used to fluorescently label antibodies and other proteins that are then used as molecular probes for cellular imaging and other fluorescence detection 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 amine-reactive DyLight 650 NHS-ester in convenient single-use vials as well as purification resin and spin columns for the preparation of ready-to-use conjugate.

DyLight 650 provides vibrant far-red fluorescence with comparable or improved performance over other dyes, including Alexa Fluor™ 647 and Cy5™ dye, for fluorescent 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 650 Amine-Reactive Dye is also available as a stand-alone reagent.

Features of DyLight 650 NHS Ester:

High performance—DyLight 650 fluoresces brighter than Alexa Fluor 647 and Cy5
Specific—NHS ester-activated dye labels proteins and other molecules at primary amines (-NH2)
Convenient kit sizes—standard and microscale sizes are offered to match your experimental needs
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 650 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 650 Amine-Reactive Dye to be provided in multiple formats with flexible protocols to achieve efficient degrees of labeling.

Related Products
DyLight™ 650 NHS Ester
DyLight™ 650 Microscale Antibody Labeling Kit

Alexa Fluor™ 568 NHS Ester (Succinimidyl Ester) (Invitrogen™)

Alexa Fluor® 568 is a bright orange dye. Used for stable signal generation in imaging and flow cytometry, Alexa Fluor® 568 dye is water soluble and pH-insensitive from pH 4 to pH 10. In addition to reactive dye formulations, we offer Alexa Fluor® 568 dye conjugated to a variety of antibodies, peptides, proteins, tracers, and amplification substrates optimized for cellular labeling and detection (learn more).

The NHS ester (or succinimidyl ester) of Alexa Fluor® 568 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® 568 dye
Reactive group: NHS ester
Reactivity: Primary amines on proteins and ligands, amine-modified oligonucleotides
Ex/Em of the conjugate: 578/602 nm
Extinction coefficient: 88,000 cm-1M-1
Spectrally similar dyes: Rhodamine Red
Molecular weight: 791.8

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.

Influx™ Pinocytic Cell-Loading Reagent (Invitrogen™)

Influx pinocytic cell-loading reagent provides a convenient, rapid and simple procedure for loading water-soluble materials into live cells. With the Influx reagent, polar compounds can be introduced into many cells simultaneously without significantly altering normal cell function.

EZ-Link™ NHS-SS-PEG4-Biotin (Thermo Scientific™)

Thermo Scientific EZ-Link NHS-SS-PEG4-Biotin includes disulfide and polyethylene glycol (PEG) groups in its spacer arm to provide biotinylation that is cleavable and which enhances solubility.

Features of EZ-Link NHS-SS-PEG4-Biotin:

Protein labeling—biotinylate antibodies or other proteins for detection or purification using streptavidin probes or resins
Amine-reactive—reacts with primary amines (-NH2), such as the side-chain of lysines (K) 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
Pegylated—spacer arm contains a hydrophilic, 4-unit, polyethylene glycol (PEG) group
Enhances solubility—pegylation imparts water solubility to the biotinylated molecule, helping to prevent aggregation of biotinylated antibodies stored in solution
Long reach—spacer arm (total length added to target) is 37.9 angstroms; this reduces steric hindrance when binding to avidin molecules

NHS-SS-PEG4-Biotin enables simple and efficient biotin labeling of antibodies, proteins and other primary amine-containing macromolecules. The N-hydroxysuccinimide ester (NHS ester) group reacts specifically and efficiently with protein and peptide lysine (K) and N-terminal amino groups at pH 7-9 to form stable amide bonds. The hydrophilic polyethylene glycol (PEG) spacer arm imparts water solubility that is transferred to the biotinylated molecule, thus reducing aggregation of labeled proteins stored in solution. The integral disulfide bond enables the biotin group to be cleaved from the labeled molecule using DTT or other reducing agents, providing for efficient recovery of avidin-bound protein complexes in affinity-based assays.

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.

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.

DyLight™ 800 NHS Ester (Thermo Scientific™)

Thermo Scientific DyLight 800 Amine-Reactive Dye is an NHS ester-activated derivative of high-performance DyLight 800 used to fluorescently label antibodies and other proteins that are then used as molecular probes for cellular imaging and other fluorescence detection methods.

DyLight 800 is a near-IR fluor that is invisible to the naked eye but increases the staining options when using infrared imaging systems. DyLight 800 has spectral properties that are very similar to other near-IR dyes, including Alexa Fluor™ 790 and IRDye™ 800. 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 800 Amine-Reactive Dye is also available as part of two antibody labeling kit sizes.

Features of DyLight 800 NHS Ester:

High performance— DyLight 800 replaces Alexa Fluor 800 and IRDye 800 for near-infrared staining
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 800 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 800 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 800 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 800 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™ 800 Antibody Labeling Kit
DyLight™ 800 Microscale Antibody Labeling Kit

Pacific Blue™ C5-Maleimide (Invitrogen™)

Pacific Blue™ C5-maleimide is an excellent reagent for thiol-selective modification, quantitation and analysis. In this reaction, the thiol is added across the double bond of the maleimide to yield a thioether. This compound does not react with methionine, histidine or tyrosine. Reaction of Pacific Blue™ C5-maleimide with amines usually requires a higher pH than reaction of maleimides with thiols.

View all Pacific Blue™ dye products..

View the Fluorophore Selection Guide.

DSB-X™ Biotin 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.

APTS (8-Aminopyrene-1,3,6-Trisulfonic Acid, Trisodium Salt) (Invitrogen™)

The aromatic amine of APTS (8-aminopyrene-1,3,6-trisulfonic acid, trisodium salt) can be reversibly coupled to aldehydes and ketones to form a Schiff base - which can be reduced to a stable amine derivative by sodium borohydride (NaBH4) or sodium cyanoborohydride (NaCNH3) to form new biotinylated probes.

Zenon™ Allophycocyanin Human IgG Labeling Kit (Invitrogen™)

Zenon labeling technology provides a fast, versatile and reliable method for producing antibody conjugates, even with very small (submicrogram) amounts of starting material. Antibody conjugates formed using Zenon technology may be used to stain cells in any protocol where a directly labeled primary antibody is suitable, including flow cytometry, imaging, high throughput and other applications. Moreover, this technology simplifies applications that previously were time consuming or not practical, such as the use of multiple mouse-derived antibodies in the same staining protocol.

View a selection guide for all Zenon™ antibody labeling kits and other antibody labeling products.

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.

Biotin-XX, SE (6-((6-((Biotinoyl)Amino)Hexanoyl)Amino)Hexanoic Acid, Succinimidyl Ester) (Invitrogen™)

The amine-reactive biotin-XX, SE can be used to attach this important hapten to biomolecules of interest for subsequent detection with streptavidin, avidin or NeutrAvidin® biotin-binding protein. This molecule has a 14 atom spacer designated by "XX" to facilitate reactivity with the molecule and eventual accessibility of the biotin to avidin or streptavidin.

DyLight™ 594 NHS Ester (Thermo Scientific™)

Thermo Scientific DyLight 594 Amine-Reactive Dye is an NHS ester-activated derivative of high-performance DyLight 594 used to fluorescently label antibodies and other proteins that are then used as molecular probes for cellular imaging and other fluorescence detection methods.

DyLight 594 provides vibrant red fluorescence with better performance than Alexa Fluor™ 594 and Texas Red™ dye for fluorescent 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 594 Amine-Reactive Dye is also available as part of two antibody labeling kit sizes.

Features of DyLight 594 NHS Ester:

High performance—DyLight 594 shows brighter fluorescence than Alexa Fluor 594 and Texas Red
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 594 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 DyLight 594 Amine-Reactive 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 594 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 594 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 594 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™ 594 Antibody Labeling Kit
DyLight™ 594 Microscale Antibody Labeling Kit

Zenon™ Horseradish Peroxidase 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

Alexa Fluor™ 555 NHS Ester (Succinimidyl Ester) (Invitrogen™)

Alexa Fluor® 555 is a bright orange dye. Used for stable signal generation in imaging and flow cytometry, Alexa Fluor® 555 dye is water soluble and pH-insensitive from pH 4 to pH 10. In addition to reactive dye formulations, we offer Alexa Fluor® 555 dye conjugated to a variety of antibodies, peptides, proteins, tracers, and amplification substrates optimized for cellular labeling and detection (learn more).

The NHS ester (or succinimidyl ester) of Alexa Fluor® 555 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® 555 dye
Reactive group: NHS ester
Reactivity: Primary amines on proteins and ligands, amine-modified oligonucleotides
Ex/Em of the conjugate: 555/572 nm
Extinction coefficient: 155,000 cm-1M-1
Spectrally similar dyes: tetramethylrhodamine
Molecular weight: ~1250

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.

Click-IT™ Palmitic Acid, Azide (15-Azidopentadecanoic Acid) (Invitrogen™)

Identify and characterize palmitylated proteins with Click-iT® palmitic 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.

2',7'-Difluorofluorescein (Oregon Green™ 488) (Invitrogen™)

Oregon Green® 488 can be used as a reference standard for Oregon Green® 488 conjugates or a pH sensor of moderately acidic solutions (pKa ~4.7)

EZ-Link™ Biotin-LC-Hydrazide (Thermo Scientific™)

Thermo Scientific EZ-Link Hydrazide-LC-Biotin is a mid-length, simple, hydrazide-activated biotinylation reagent for labeling glycoproteins and other carbohydrate-containing compounds having oxidizable sugars or aldehydes.

Features of EZ-Link Biotin-LC-Hydrazide:

Glycoprotein labeling—biotinylate glycosylated proteins at sialic acid residues for detection or purification using streptavidin probes or resins
Cell surface labeling—biotinylate and isolate cell surface glycoproteins
Aldehyde-reactive—reacts with aldehydes formed by periodate-oxidation of sugar groups
Hydrazide-activated—perform reactions at pH 4 to 6 in buffers such as sodium acetate
Irreversible—forms semi-permanent hydrazone bonds; spacer arm cannot be cleaved
Solubility—usually dissolved in DMSO before further dilution in aqueous buffers
Spacer arm length—24.7Å

This biotin hydrazide reagent enables simple and efficient biotin labeling of polyclonal antibodies and other glycoproteins. Mild oxidation of antibodies with sodium periodate produces reactive aldehydes on the carbohydrate moieties of the Fc portion that can be modified by hydrazides. This approach is advantageous for labeling antibodies because biotinylation occurs only at the sites of glycosylation, which are primarily in the Fc region of the antibody, far from the antigen binding site.

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. Hydrazides and alkoxyamines are two types of carbonyl-reactive groups. Hydrazides (—NH-NH2) react specifically with aldehyde groups in slightly acidic conditions to form hydrazone linkages; these can be further reduced to stable secondary amine bonds using sodium cyanoborohydride (Part No. 44892). The reaction is more efficient in the presence of aniline (Part No. 88944). Alternatively, hydrazides can be conjugated to carboxylic acids using EDC carbodiimide chemistry.

Reactive aldehyde groups can be generated in glycoproteins and other polysaccharide compounds by oxidation of constituent sugar diols using sodium periodiate (Part No. 20504). Sialic acid residues are common components of protein glycosylation and are easily converted to aldehydes with 1 mM NaIO4.

Related Products
EZ-Link™ Hydrazide-Biotin

Click-IT™ Maleimide DIBO Alkyne, for copper free click chemistry (Invitrogen™)

Conjugates prepared with this thiol-reactive maleimide DIBO alkyne, can be detected with an azide-containing molecule in a copper-free click chemistry reaction. Click chemistry describes a class of chemical reactions that use bio-orthogonal or biologically unique moities to label and detect a molecule of interest using a two-step procedure. The two-step reaction procedure involves triazole formation of an azide and an alkyne. Click reactions have several characteristics: the reaction between the detection moieties is efficient; no extreme temperatures or solvents are required; the reaction product is stable; the components of the reaction are bioinert; and perhaps most importantly, no side reactions occur, and with the elimination of copper, no detectable damage to cells or proteins. Unlike traditional chemical reactions utilizing succinimidyl esters or maleimides that target amines and sulfhydryls – functional groups that are not unique – click chemistry-labeled molecules can be applied to complex biological samples and be detected with unprecedented sensitivity due to extremely low background.

BODIPY™ FL Iodoacetamide (BODIPY™ FL C1-IA, N-(4,4-Difluoro-5,7-Dimethyl-4-Bora-3a,4a-Diaza-s-Indacene-3-yl)Methyl)Iodoacetamide) (Invitrogen™)

The thiol-reactive BODIPY® FL iodoacetamide can be used to create green-fluorescent bioconjugates. The electronically neutral BODIPY® FL dye has the most fluorescein-like spectra of the green-fluorescent BODIPY® dyes.

Alexa Fluor™ 555 alkyne, Triethylammonium Salt (Invitrogen™)

The orange-fluorescent Alexa Fluor® 555 alkyne is designed to react with azide-containing molecules via the fast, selective and extremely efficient copper-catalyzed “click" reaction.

EZ-Link™ Alkoxyamine-PEG12-Biotin (Thermo Scientific™)

Thermo Scientific EZ-Link Alkoxyamine-PEG12-Biotin is a biotinylation reagent containing a long, 12-unit polyethylene glycol (PEG) spacer for biotinylating macromolecules at carbohydrate groups that have been oxidized to form aldehydes.

Features of EZ-Link Alkoxyamine-PEG12-Biotin:

Glycoprotein labeling—biotinylate glycosylated proteins at sialic acid residues for detection or purification using streptavidin probes or resins
Cell surface labeling—biotinylate and isolate cell surface glycoproteins; reagent does not permeate membranes of whole cells
Aldehyde-reactive—reacts with aldehydes formed by periodate-oxidation of sugar groups
Alkoxyamine-activated—aminooxy group forms more stable linkages than hydrazide reagents
Pegylated—spacer arm contains a hydrophilic, 12-unit, polyethylene glycol (PEG) group
Enhances solubility—pegylation imparts water solubility to the biotinylated molecule, helping to prevent aggregation of biotinylated antibodies stored in solution
Irreversible—forms stable (permanent) oxime bonds; spacer arm cannot be cleaved
Solubility—usually dissolved in DMSO to make concentrated stock solution
Long reach—spacer arm (total length added to target) is 55.4 angstroms

Aminooxy-biotin reagents such as this one are useful for biotinylating glycoproteins and other molecules that have oxidizable polysaccharides groups. The alkoxyamine group (also called an aminooxy or aminoxy group) conjugates to aldehydes of oxidized sugars. EZ-Link Alkoxyamine-PEG-Biotin reagents contain a multi-functional extended spacer arm that is a flexible, non-immunogenic hydrophilic polyethylene glycol (PEG), which imparts water solubility to labeled molecules. Consequently, antibodies labeled with pegylated biotin reagents exhibit less aggregation when stored in solution compared to antibodies labeled with reagents having only hydrocarbon spacers.

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. Hydrazides and alkoxyamines are two types of carbonyl-reactive groups. Alkoxyamines (—O-NH2) react specifically with aldehyde groups in near-neutral conditions to form stable oxime linkages. The reaction is more efficient in the presence of aniline (Part No. 88944). Alternatively, alkoxyamines can be conjugated to carboxylic acids using EDC carbodiimide chemistry.

Reactive aldehyde groups can be generated in glycoproteins and other polysaccharide compounds by oxidation of constituent sugar diols using sodium periodiate (Part No. 20504). Sialic acid residues are common components of protein glycosylation and are easily converted to aldehydes with 1 mM NaIO4.

Biotin-X Cadaverine (5-(((N-(Biotinoyl)Amino)Hexanoyl)Amino)Pentylamine, Trifluoroacetic Acid Salt) (Invitrogen™)

The primary aliphatic amine of biotin-X cadaverine can be reversibly coupled to aldehydes and ketones to form a Schiff base - which can be reduced to a stable amine derivative by sodium borohydride (NaBH4) or sodium cyanoborohydride (NaCNH3) to form new biotinylated probes. Carboxylic acids of proteins and other water-soluble biopolymers can be coupled to this molecule in aqueous solution using water-soluble carbodiimides such as EDAC (E2247).

Qdot™ 545 ITK™ Amino (PEG) Quantum Dots (Invitrogen™)

Qdot® 545 ITK™ amino (PEG) quantum dots are the ideal starting material for preparing custom conjugates of ultrabright and photostable fluorescently labeled proteins or other biopolymers. These probes are functionalized with amine-derivatized PEG, which prevents non-specific interactions and provides a convenient handle for conjugation. The amino quantum dots react efficiently with isothiocyanates and succinimidyl esters, or with native carboxylic acids using water-soluble carbodiimides such as EDC. Such derivatives may be used for various labeling and tracking applications that require ultrabright and stable fluorescence. Our Qdot® ITK™ amino quantum dots are provided as 8 µM solutions and are available in 8 colors of Qdot® probes.

Important Features of Qdot® ITK™ Amino Quantum Dots:
• Qdot® 545 ITK™ amino quantum dot has emission maxima of ~545 nm
• Extremely photostable and bright fluorescence
• Efficiently excited with single-line excitation sources
• Narrow emission, large stokes shift
• Available in multiple colors
• Ideal for various 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 amine-derivatized form, we offer Qdot® ITK™ quantum dots with carboxyl 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.

Alexa Fluor™ 555 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.