Shop All Protein Labeling Reagents

Texas Red™-X, Succinimidyl Ester, mixed isomers Invitrogen™

The isomeric mixture of amine-reactive Texas Red-X, succinimidyl ester and its conjugates emit at a longer wavelength than do either tetramethylrhodamine or Lissamine rhodamine B, and are among the most commonly used long-wavelength "third labels" in fluorescence microscopy and flow cytometry. Protein conjugates prepared with Texas Red-X succinimidyl ester also have a higher fluorescence yield than those with the same labeling ratio prepared with Texas Red sulfonyl chloride.

Texas Red™ Hydrazide, >90% single isomer Invitrogen™

The primary aliphatic amine of the red-fluorescent Texas Red® hydrazide 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).

Sulfo-SHPP (Water-Soluble Bolton-Hunter Reagent) Thermo Scientific™

Thermo Scientific Pierce Sulfo-SHPP, sulfosuccinimidyl-3 -(4-hydroxypheynyl) propionate, also known as water-soluble Bolton-Hunter Reagent, conjugates tyrosine-like functional groups to primary amines to increase the number of tyrosyl groups that can be iodinated by iodine-125 labeling procedures.

Features of Sulfo-SHPP:

• Iodinate before or after coupling Sulfo-SHPP to the molecule of interest
• Useful for introducing tyrosyl groups on proteins sensitive to small amounts of organic solvent
• Useful for labelling cell surfaces without exposing the cells to membrane permeable solvents

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

The SAIVI Alexa Fluor 647 Antibody/Protein Labeling Kit provides the materials needed conveniently label an antibody or protein with amine-reactive far-red fluorescent Alexa Fluor 647 dye (ex/em 650/665 nm) for in vivo animal imaging applications. This kit is optimized for labeling 1 mg of IgG antibody per reaction with Alexa Fluor 647 and comparably small amounts of other proteins (>20 kDa) can also be labeled. Each kit contains everything needed for three labeling reactions, degree of labeling (DOL) modification, and subsequent purification for free dye removal. Our protein labeling kits include an easy-to-use pre-packed spin column for rapid dye removal and high antibody recovery typically greater than 85%. Stabilizing proteins must be removed from the sample before labeling.

SAIVI Alexa Fluor 647 Antibody/Protein Labeling Kit features include:
• Convenient—labeled proteins typically ready to use in 90 min (~15 min hands-on time)
• High conjugate recovery—pre-packed spin columns generally result in >85% recovery of antibody conjugate
• Simple protocol—react, separate, use; detailed instructions included for DOL determination and modification
• Rapid purification—quickly remove unbound dye with included pre-packed spin columns in under 15 minutes
To control the DOL of the antibody conjugate, the SAIVI Alexa Fluor 647 Antibody/Protein Labeling Kit includes a DOL modulating reagent and instructions for decreasing the DOL from its intrinsic highest value by adding specific amounts of this reagent to the labeling reaction. With this method, antibody preparations with varying ratios of dye to protein can be quickly and reproducibly obtained without significant alteration of labeling or purification conditions. Readily altering the DOL allows for more efficient optimization for in vivo imaging applications where the DOL of a protein can have significant effects on the signal-to-background ratio, biodistribution, and clearance.

Better results and workflows with labeled primary 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.

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. Learn more about Alexa Fluor Dyes ›.

Learn more about protein and antibody labeling
We offer a wide selection of antibody and protein labeling kits to fit your starting material and your experimental setup. Learn more about antibody labeling kits and fluorescent protein labeling.

Custom antibody conjugates
If you can’t find what you’re looking for in our stocked list, we can 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.

pHrodo™ Green S. aureus BioParticles™ Phagocytosis Kit for Flow Cytometry Invitrogen™

The pHrodo™ Green S. aureus BioParticles™ Phagocytosis Kit for Flow Cytometry enables the detection of phagocytic activity in whole blood samples and live cell lines by flow cytometry. The kit includes all the reagents required for assessing particle ingestion and red blood cell lysis. Sufficient reagents are provided in the kit for performing approximately 100 assays using 100 µL of whole blood per assay.

View a selection guide for all pHrodo Indicators used in imaging, flow cytometry and microplate assays.

The pHrodo™ Green S. aureus BioParticles™ assay provides sensitive detection without the need for quenching reagents and extra wash steps, helping save time and minimize the uncertainty of whether particle signals derive from internalized particles.

The pHrodo™ Green S. aureus BioParticles™ Phagocytosis Kit is:

• Specific—fluorogenic, pH-sensitive dye for detection of phagocytosis
• Rapid and reproducible—no wash steps or quencher dye required
• Flexible—multiplex with reagents excited by other laser lines
• Compatible—multiplex with standard reagents and CD markers

How It works
The pHrodo™ Green S. aureus BioParticles™ conjugates are inactivated, unopsonized S. aureus which function as highly sensitive, fluorogenic particles for the detection of phagocytic ingestion. The unique pHrodo™ dye-based system measures phagocytic activity based on acidification of particles as they are ingested, eliminating the wash and quenching steps that are necessary with nonfluorogenic indicators of bacterial uptake.

The pHrodo™ Green Dye
The new Molecular Probes™ proprietary, pH-sensitive, pHrodo™ Green dye is non-fluorescent at neutral pH, but turns bright green upon acidification. Because it is both fluorogenic and pH-sensitive, the pHrodo™ Green dye can be used as a specific sensor of phagocytic events; acidification of the phagosome following phagocytosis is marked by green fluorescence. It is therefore an ideal tool with which to study phagocytosis and its regulation by drugs and/or environmental factors.

The fluorophore is readily excited with the 488 nm argon-ion laser and fluorescence emission can be collected using a standard 530/30 nm BP filter on most flow cytometers, and thus is easily multiplexable with reagents used on other lasers .

Rapid and reproducible
Wash steps and quencher dyes are not needed, since the pHrodo™ Green dye is non-fluorescent outside the cell, making the staining protocol simple and fast. The elimination of wash steps and quencher dyes also improves assay reproducibility, particularly in plate reader-based assays.

Use with bacteria
Analysis of phagocytosis by Gram-positive or Gram-negative bacteria is easily accomplished using the ready-made pHrodo™ Green BioParticles™ conjugates. Use ready-made pHrodo™ Green BioParticles™ conjugates for convenient analysis of phagocytosis of Gram-positive or Gram-negative bacteria, or the amine-reactive pHrodo™ Green STP ester for labeling microorganisms or proteins of your choice.

pHrodo™ Indicators for Phagocytosis
The pHrodo™ Green S. aureus BioParticles™ Phagocytosis Kit is part of a larger product offering of reagents for measurement of phagocytosis. Scientists can use a variety of pHrodo™ reagents in plate readers, fluorescence microscopy imaging and flow cytometry.

Additional information about pHrodo™ Green products, pHrodo™ Red products, and other pHrodo™ indicators for phagocytosis.

pHrodo™ Green AM Intracellular pH Indicator Invitrogen™

pHrodo Green AM Intracellular pH Indicator is a novel fluorogenic probe used to measure intracellular pH in live cells. pHrodo Green is weakly fluorescent at neutral pH but increasingly fluorescent as the pH drops. This reagent can quantify cellular cytosolic pH in the range of 9-4 with a pKa of ~6.5 with excitation/emission of 509/533 nm. pHrodo Green is photostable and appropriate for use in multiplexing experiments with red and deep red fluorophores such as RFP, Alexa Fluor 594, MitoTracker Red, and MitoTracker Deep Red.

This pHrodo Green dye has been modified with AM ester groups, which results in an uncharged molecule that can permeate cell membranes. Once inside the cell, the lipophilic blocking groups are cleaved by nonspecific esterases, resulting in a compound that is retained within the intracellular space. Fluorescence intensity of the probe is then an indicator of intracellular pH. Subsequent use of the Intracellular pH Calibration Buffer Kit (Cat. No. P35379) allows this intracellular pH to be quantified.

pHrodo Green AM Intracellular pH Indicator is compatible with various platforms, such as traditional fluorescence microscopy, high content screening (HCS), flow cytometry, and microplate-based fluorimetry or high throughput screening (HTS). This reagent is also compatible with various benchtop instruments such as the Evos, FLoid, Tali, and Attune instruments.

Alexa Fluor™ 647 Hydrazide Invitrogen™

Alexa Fluor® 647 Hydrazide is useful as a cell tracer and as a reactive dye for labeling aldehydes or ketones in polysaccharides or glycoproteins. Alexa Fluor® 647 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® 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).

Detailed information about this AlexaFluor® hydrazide:

• Fluorophore label : Alexa Fluor® 647 dye
• Reactive group: hydrazide
• Reactivity: Aldehydes or keytones in polysaccharides or glycoproteins
• Ex/Em of the conjugate: 649/666 nm
• Extinction coefficient: 250,000 cm-1M-1
• Spectrally similar dyes: APC, Cy5
• Molecular weight: ~1,200

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)

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.

BS3 (bis(sulfosuccinimidyl)suberate), No-Weigh™ Format Thermo Scientific™

Thermo Scientific Pierce BS3 (Sulfo-DSS) is bis(sulfosuccinimidyl)suberate, an amine-to-amine crosslinker that is homobifunctional, water-soluble, non-cleavable and membrane impermeable.

BS3 contains an amine-reactive N-hydroxysulfosuccinimide (NHS) ester at each end of an 8-carbon spacer arm. NHS esters react with primary amines at pH 7-9 to form stable amide bonds, along with release of the N-hydroxysulfosuccinimide leaving group. Proteins, including antibodies, generally have several primary amines in the side chain of lysine (K) residues and the N-terminus of each polypeptide that are available as targets for NHS-ester crosslinking reagents.

No-Weigh microtube handling:
Each of the eight microtubes contains 2 mg of crosslinker. Puncture foil with a pipette tip and add DMSO or DMF to the DSS or aqueous buffer to the BS3. Store the microtube strip in the foil pouch provided. Used microtubes may be cut from the unused microtubes and discarded.

Features of BS3:

Reactive groups: sulfo-NHS ester (both ends)
Reactive towards: amino groups (primary amines)
• Amine-reactive Sulfo-NHS ester reacts rapidly with any primary amine-containing molecule
• Water-soluble; compare with DSS
• Membrane-impermeable, allowing for cell surface labeling
• High-purity, crystalline reagent can be used to create high-purity crosslinked conjugates

Because it contains the hydrophilic sulfonyl moiety, BS3 crosslinker is soluble up to ~100 mM in water and many commonly used buffers, thus avoiding the use of organic solvents which may perturb protein structure. DSS, the non-water soluble analog of BS3 is also available for applications that require a less hydrophilic crosslinker (e.g., to effect intracellular crosslinking). DSS and BS3 have essentially identical crosslinking activity toward primary amines.

Properties of BS3:
• Alternative names: Sulfo-DSS
• Molecular formula: C16H18N2O14S2Na2
• Molecular weight: 572.43
• Spacer arm length: 11.4 Å (8 atoms)
• CAS number: 82436-77-9
• Reactive groups: NHS esters, react with primary amines at pH 7.0-9.0

Applications:
• Crosslink cell-surface proteins prior to cell lysis and immunoprecipitation
• Identify receptor-ligand interactions by chemical crosslinking
• 'Fix' protein interactions to allow identification of weak or transient protein interactions
• Identify near-neighbor protein interactions
• Protein crosslinking to create bioconjugates via single-step reactions
• Immobilize proteins onto amine-coated surfaces

BS3 Specifications:
We manufacture BS3 to the highest specifications to produce the most specific bioconjugates, ensure the integrity of your data and to provide you with the highest degree of consistency. Each lot of BS3 is tested to meet the following minimum specifications:
• Purity: > 93% by quantitative NMR (the highest standard for crosslinker purity)
• Solubility: > 5.8 mg/mL in DI water, clear solution with no insoluble material

Product References
Crosslinker Application Guide -- search for recent literature references for this product

Related Products
Pierce™ Premium Grade BS3
DSS (disuccinimidyl suberate)
BS(PEG)5 (PEGylated bis(sulfosuccinimidyl)suberate)
BS(PEG)9 (PEGylated bis(sulfosuccinimidyl)suberate)

SAIVI™ Rapid Antibody Labeling Kit, Alexa Fluor™ 750 Invitrogen™

The Alexa Fluor® 750 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.

Image-iT™ Green Hypoxia Reagent Invitrogen™

Image-iT Green Hypoxia Reagent is a novel, fixable fluorogenic compound for measuring hypoxia in live cells. It is non-fluorescent when live cells are in an environment with normal oxygen concentrations and becomes fluorescent when oxygen levels are decreased. Image-iT Green Hypoxia Reagent sustains its fluorescence when cells/tissue return to normal oxygen levels, allowing the cells/tissue to be fixed with minimal loss of fluorescent signal.

Features of Image-iT Green Hypoxia Reagent include:
• Indicates hypoxia in live cells by fluorescing in low oxygen environments
• Fixable—sustains fluorescent signal when cells/tissue return to normal oxygen levels
• Easy to use—just add to cell culture media and image

Image-iT Green Hypoxia Reagent is a fluorogenic compound that is live cell permeable and becomes fluorescent in environments with low oxygen concentrations. These properties makes it a highly useful tool for detecting cells and tissue under hypoxic conditions. Image-iT Green Hypoxia Reagent is a very sensitive oxygen detector. Unlike pimonidazole adducts that respond only to very low oxygen levels, Image-iT Green Hypoxia Reagent begins to fluoresce when atmospheric oxygen levels are less than 5%. It responds quickly to such environments, and the fluorescence is sustained after the oxygen levels return to normal. These properties make Image-iT Green Hypoxia Reagent an ideal tool for detecting hypoxic conditions around tumors, 3D cultures, spheroids, neurons, etc.

DyLight™ 405 NHS Ester Thermo Scientific™

Thermo Scientific DyLight 405 Amine-Reactive Dye is an NHS ester-activated derivative of high-performance DyLight 405 used to fluorescently label antibodies and other proteins that are then used as molecular probes for cellular imaging and other fluorescence detection methods.

DyLight 405 has a vibrant blue fluorescence intensity that replaces Alexa Fluor™ 405, Cascade™ Blue and AMCA in many 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 405 Amine-Reactive Dye is also available as part of two antibody labeling kit sizes.

Features of the DyLight 405 Amine-Reactive Dye:

High performance— DyLight 405 shows bright fluorescence and replaces Alexa Fluor 405, Cascade Blue and AMCA
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 405 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 405 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 405 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 405 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™ 405 Antibody Labeling Kit
DyLight™ 405 Microscale Antibody Labeling Kit

Alexa Fluor™ 488 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 hr (~30 min 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 tetrafluorophenyl (TFP) ester moiety that is more stable in solution than the commonly used succinimidyl (NHS) ester. TFP esters react efficiently 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.

Zenon™ Mouse IgG1 Labeling Kit Invitrogen™

Simplify your multicolor staining and flow cytometry experiments with our Zenon™ mouse IgG1 labeling kits. These antibody labeling kits are ideal for flow cytometry (e.g., FACS) experiments because they enable the simultaneous labeling of different target cells and tissues with differently labeled mouse monoclonal antibodies in a single staining protocol. Multiple Zenon™ antibody complexes may be prepared individually and used in a multicolor stain after using the Zenon™ blocking reagent.

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.
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