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EZ-Link™ Maleimide Activated Horseradish Peroxidase Kit (Thermo Scientific™)

Thermo Scientific Pierce Maleimide Activated Horseradish Peroxidase Kit is for preparation of HRP conjugates with proteins, peptides or other ligands that contain sulfhydryl groups, such as reduced cysteines. It is sufficient fo the conjugation of 5 mg of immunoglobulin (IgG). The kit contains all buffers and one 10 mL desalting column.

Features of the Maleimide Activated Horseradish Peroxidase Kit :

Activated HRP – horseradish peroxidase (HRP) modified with maleimide groups for conjugation to sulfhydryl molecules
Sulfhydryl-reactivemaleimide groups conjugate to reduced thiols (-SH), as in the side-chain of cysteine residues
High activity HRP – enzyme activity is greater than 240 units/mg; lyophilized, activated enzyme is stable for at least 12 months at 4°C
Complete kit – includes the activated HRP as well as two types of reagents for sulfhydryl-ready antibodies (IgG) or proteins for conjugation

This product consists of horseradish peroxidase (HRP) that has been modified with Sulfo-SMCC (Part No. 22322) to attach several maleimide groups per HRP molecule while retaining the peroxidase activity. The activated HRP will covalently attach to proteins or other molecule containing sulfhydryl groups (e.g., cysteines). HRP-conjugates of antibodies, proteins, peptides and other thiol-containing reporter probes are easily made using this method. The complete kit includes the activated HRP as well as two types of reagents for preparing sulfhydryl-ready antibodies (IgG) or proteins for conjugation.

The complete kit for Maleimide Activated Horseradish Peroxidase contains reagents for exposing or added the necessary sulfhydryl groups on antibodies (IgG) or practically any other protein. These general strategies are described briefly in the applications section of our review of Maleimide Reaction Chemistry. Of course, any protein that contains cysteines has sulfhydryl groups (-SH), but they must be reduced (not in the form of disulfide bonds) to be conjugated. Antibodies also contain disulfide bonds that can be targeted as antibody labeling sites; the hinge-region disulfide bonds in IgG can be selectively cleaved with the mild reducing agent 2-Mercaptoethylamine (Part No. 20408), which is included in the complete kit. Alternatively, sulfhydryl groups can be added to proteins (or any amine-containing molecule) using SATA reagent (Part No. 26102), which also is included in the kit.

Related Products
EZ-Link™ Maleimide Activated Horseradish Peroxidase

5-ROX, SE (5-Carboxy-X-Rhodamine, Succinimidyl Ester), single isomer (Invitrogen™)

The isomeric 5-ROX, SE is an amine-reactive form of carboxy-X-rhodamine and is widely used for oligonucleotide labeling and automated DNA sequencing applications.

5-SFX (6-(Fluorescein-5-Carboxamido) Hexanoic Acid, Succinimidyl Ester), single isomer (Invitrogen™)

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

Molecular Probes® Cell Imaging Kit (Invitrogen™)

Fluorescence imaging protocols are sometimes complicated and tedious, with more time spent preparing samples and reagents than acquiring images and data. To help researchers focus more on biology and get results faster, we have developed a set of imaging reagents that emphasize user friendliness and workflow convenience.

The Molecular Probes® Cell Imaging Kit contains the following products:

NucBlue™ Live ReadyProbes™ Reagent (Cat. No. R37605)
NucRed™ Live 647 ReadyProbes™ Reagent (Cat. No. R37106)
ReadyProbes™ Cell Viability Imaging Kit, Blue/Green (Cat. No. R37609)
Goat Anti-Rabbit IgG (H+L) Secondary Antibody, Alexa Fluor™ 594 conjugate (Cat. No. R37117)
Goat Anti-Mouse lgG Secondary Antibody, Alexa Fluor™ 488 conjugate (Cat. No. R37120)
Image-iT™ FX Signal Enhancer ReadyProbes™ Reagent (Cat. No. R37107)

Zenon™ Allophycocyanin Rabbit 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.

CellVue™ Lavender 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™ Lavender is a violet fluorescent cell labeling reagent. It is optimally excited at 420 nm and has a peak emission of 461 nm. CellVue™ Lavender is compatible with most multi-color flow cytometric applications; however, due to similar emission properties it cannot be used in combination with eFluor™ 450 or Pacific Blue™ reagents.

Reported Application
Flow Cytometric Analysis, Microscopy, Immunocytochemistry, Cell Labeling

Zenon™ Alexa Fluor™ 555 Mouse IgG2a Labeling Kit (Invitrogen™)

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

Important Features of Zenon® Labeling Technology:

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


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

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

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

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

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

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

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

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

Related Links:

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

EZ-Link™ Alkoxyamine-PEG4-Biotin (Thermo Scientific™)

Thermo Scientific EZ-Link Alkoxyamine-PEG4-Biotin is a biotinylation reagent containing a four-unit polyethylene glycol (PEG) spacer for biotinylating macromolecules at carbohydrate groups that have been oxidized to form aldehydes.

Features of EZ-Link Alkoxyamine-PEG4-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, 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
Irreversible—forms stable (permanent) oxime bonds; spacer arm cannot be cleaved
Solubility—usually dissolved in DMSO to make concentrated stock solution
Medium length—spacer arm (total length added to target) is 27.0 angstroms, sufficient to minimize steric hindrance for binding

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.

Acryloyl-X, SE, 6-((acryloyl)amino)hexanoic Acid, Succinimidyl Ester (Invitrogen™)

The succinimidyl ester of acryloyl-X, SE (6-((acryloyl)amino)hexanoic acid) reacts with amines, of proteins, amine-modified nucleic acids and other biomolecules to yield acrylamides that can be copolymerized into polyacrylamide matrices or on surfaces, such as in microarrays and in biosensors.

Click-iT™ Alexa Fluor™ 647 sDIBO Alkyne (Invitrogen™)

Click-iT Alexa Fluor 647 sDIBO Alkyne reacts with azides via a copper-free Click chemistry reaction to produce fluorescent Alexa Fluor 647 bioconjugates. sDIBO alkynes are improved versions of our original DIBO cyclooctynes, yielding conjugates that are less “sticky” and give lower signal background in biological samples. Copper-free Click bio-conjugation reactions are ideal for surface labeling of live cells and also minimize damage to enzymes and fluorescent proteins like GFP or R-PE. Macromolecules that have been azide-modified enzymatically, chemically, or metabolically can be now be labeled easily, yielding more soluble bioconjugates with improved biological labeling utility.

• More soluble than DIBO cyclooctynes leading to more soluble conjugates
• Minimal background potential in cells and tissues compared to original DIBO cycloctynes

Learn more about Alexa Fluor dyes ›

Fluoresceinyl Glycine Amide (5-(Aminoacetamido)Fluorescein) (Invitrogen™)

The primary aliphatic amine of 5-(aminoacetamido)fluorescein (fluoresceinyl glycine amide) 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 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). The glycine may be the better amine probe for direct carbodiimide-mediated coupling, since it is likely to remain unprotonated at a lower pH than other aliphatic amines.

DyLight™ 488, Free Acid (Thermo Scientific™)

Thermo Scientific DyLight Fluor Free Acids are non-activated forms of selected DyLight Fluorescent Dyes for use as controls and calibration factors in fluorescence imaging applications. DyLight 488 has excitation and emission peaks at 493 and 518 nm, respectively (±4 nm, in PBS).

These non-activated fluorescent dyes contain the native carboxyl group of the standard dye molecule.

General DyLight Fluorophore Highlights:

Bright fluorescence—intense emission provides superior sensitivity and requires less conjugate
Narrow emission spectra—negligible bleed-through between fluorophore channels enables multi-color detection
Excellent photostability—exceptional resistance to photobleaching enables fluorescence imaging under the most demanding conditions (e.g., structured illumination, 4Pi microscopy)
Buffer stability—conjugated fluorophores are completely stable at pH 4-9
Instrument compatibility—excitation and emission spectra correspond with filter sets and laser settings of all popular fluorescence instrumentation

Related Products
DyLight™ 747, Free Acid
DyLight™ 800, Free Acid

Alexa Fluor™ 568 Hydrazide, for microinjection (Invitrogen™)

Alexa Fluor® 568 Hydrazide is useful as a cell tracer and as a reactive dye for labeling aldehydes or ketones in polysaccharides or glycoproteins. This version is formatted as a ready-to-use solution that is dissolved in a 200 mM KCl solution and filter sterilized.

Alexa Fluor® 568 is a bright, red fluorescent 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).

Detailed information about this AlexaFluor® hydrazide:

• Fluorophore label : Alexa Fluor® 568 dye
• Reactive group: hydrazide
• Reactivity: Aldehydes or keytones in polysaccharides or glycoproteins
• Ex/Em of the conjugate: 576/599 nm
• Extinction coefficient: 86,000 cm-1M-1
• Spectrally similar dyes: Rhodamine Red
• Molecular weight: 730.74

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. It is designed to be loaded into cells by microinjection or infusion from patch pipette. 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)

Qtracker™ 705 Cell Labeling Kit (Trial Size) (Invitrogen™)

The Qtracker® 705 Cell Labeling Kit uses a custom targeting peptide to deliver near-infrared fluorescent Qdot® 705 probe (ex/em 405–665/705 nm) into the cytoplasm of live cells. Once inside the cells, the Qdot® 705 probe provides an intense, stable fluorescence that can be traced through several generations and is not transferred to adjacent cells in a population. This trial-size version offers a convenient introduction to the Qtracker® cell labeling technology at an affordable price.

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

Features of the Qtracker® Cell Labeling kits include:

• Qtracker® probes allow for continuous illumination, without photobleaching or degradation problems often associated with organic dyes
• Simple to use—add Qtracker® labeling solution to cells in serum-containing media, incubate one hour, then detect and track the cells
• Provide an intense, stable fluorescence that can be traced through several generations
• Excellent tool for long-term tracking or imaging studies of live cells, including migration, motility, morphology, and other cell function assays

The Qtracker® Cell Labeling kits use a custom targeting peptide to deliver Qdot® probes into the cytoplasm of live cells. Since the cytoplasmic delivery mechanism is not mediated by a specific enzyme, no cell-type specificity has been observed. Maximum delivery is typically accomplished in less than 1 hour.

The Qdot® probes are compatible with serum-sensitive cells. The intense fluorescence from the Qdot® probes is maintained in complex cellular environments and under various biological conditions including changes in intracellular pH, temperature, and metabolic activity.

Long-Lasting, Targeted Signal
Use of Qtracker® Cell Labeling kits results in the ability to observe labeled cells with extensive continuous illumination, without photobleaching or degradation problems often associated with organic dyes. Once inside the cells, the Qdot® probes are localized to cytoplasmic vesicles and are inherited by daughter cells for at least six generations. Fluorescence from the Qdot® probes can be detected for up to a week after delivery in some cell lines. The long-term cellular retention of the Qdot® probes results in an ideal tool for studying cell motility, migration, differentiation, morphology, and many other cellular function studies. Since the Qtracker® labels do not leak out of intact labeled cells and are not transferred to adjacent cells, the Qtracker® Cell Labeling kits result in a targeted signal.

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

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

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

Click-IT™ Geranylgeranyl Alcohol, Azide, mixed isomers (Invitrogen™)

Identify and characterize geranylated proteins with Click-iT® geranylgeranyl alcohol, 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.