Shop All Thiol-Reactive Fluorophores, Biotins & Other Labels

Oregon Green™ 488 Iodoacetamide, mixed isomers Invitrogen™

The thiol reactive Oregon Green® 488 iodoacetamide can be used to can be used to create green fluorescent bioconjugates with excitation/emission maxima ~496/524 nm.
This fluorinated analog of fluorescein overcomes some of the key limitations of fluorescein, including greater photostability and a lower pKa (pKa ~ 4.7 versus 6.4 for fluorescein), making its fluorescence essentially pH insensitive in the physiological pH range.

Oregon Green™ 488 Maleimide Invitrogen™

The thiol reactive Oregon Green® 488 maleimide can be used to can be used to create green fluorescent bioconjugates with excitation/emission maxima ~496/524 nm.
This fluorinated analog of fluorescein overcomes some of the key limitations of fluorescein, including greater photostability and a lower pKa (pKa ~ 4.7 versus 6.4 for fluorescein), making its fluorescence essentially pH insensitive in the physiological pH range.

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.

N-(1-Pyrene)Maleimide Invitrogen™

The thiol-reactive N-(1-pyrene)maleimide can be used to create environment-sensitive bioconjugates with this unique fluorophore.

Monobromobimane (mBBr), 25 mg Invitrogen™

Monobromobimane is essentially nonfluorescent until conjugated, readily reacts with several low molecular weight thiols, including glutathione, N-acetylcysteine, mercaptopurine, peptides and plasma thiols. The glutathione conjugate of monobromobimane has absorption/emission maxima ~394/490 nm.

Tetramethylrhodamine-5-Maleimide, single isomer Invitrogen™

Tetramethylrhodamine-5-maleimide is a thiol-reactive dye that yields photostable, pH-insensitive, red-orange—fluorescent conjugates.

Tris-(2-Carboxyethyl)phosphine, Hydrochloride (TCEP) Invitrogen™

Disufide crosslinks of cystines in proteins can be reduced to cysteine residues by TCEP (tris-(2-carboxyethyl)phosphine). Unlike DTT (dithiothreitol), TCEP does not contain thiols and therefore usually does not need to be removed prior to thiol modification.

DyLight™ 350 Maleimide Thermo Scientific™

Thermo Scientific DyLight 350 Sulfhydryl-Reactive Dye is a maleimide-activated derivative of high-performance DyLight 350 used to fluorescently label sulfhydryl-containing peptides, proteins and other biomolecular probes.

DyLight 350 has high fluorescence intensity over a broad pH range (pH 4-9) and is more photostable than Alexa Fluor™ 350 and AMCA dyes 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.

Features of DyLight 350 Sulfhydryl-Reactive Dye:

High performance—DyLight 350 shows brighter fluorescence than Alexa Fluor 350 and AMCA
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 350 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.

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DyLight™ 350 Maleimide

Pierce™ Streptavidin, Hydrazide-Activated Thermo Scientific™

Thermo Scientific Pierce Hydrazide-Activated Streptavidin conjugate include recombinant streptavidin in a purified form activated for crosslinking to carbonyl groups in a molecule.

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Pierce™ Streptavidin
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Pierce™ Streptavidin, Alkaline Phosphatase Conjugated
Pierce™ Streptavidin, Maleimide-Activated

6-IAF (6-Iodoacetamidofluorescein) Invitrogen™

The thiol-reactive 6-iodoacetamidofluorescein (6-IAF) can be used to produce bioconjugates with the 5-isomer of fluorescein.

Monochlorobimane (mBCI) Invitrogen™

Monochloromobimane is essentially nonfluorescent until conjugated, readily reacts with several low molecular weight thiols, including glutathione, N-acetylcysteine, mercaptopurine, peptides and plasma thiols. The glutathione conjugate of monochlorobimane has absorption/emission maxima ~394/490 nm.

IANBD Amide (N,N'-Dimethyl-N-(Iodoacetyl)-N'-(7-Nitrobenz-2-Oxa-1,3-Diazol-4-yl)Ethylenediamine) Invitrogen™

The thiol-reactive IANBD amide can be used to create environment sensitive probes. The absorption and fluorescence emission spectra, quantum yields, and extinction coefficients of NBD conjugates are all markedly dependent on solvent. Additionally, NBD is also a function analog of the dinitrophenyl hapten, and its fluorescence is quenched upon binding to anti-dinitrophenyl (anti-DNP) antibodies.

N-(Biotinoyl)-N'-(Iodoacetyl)Ethylenediamine Invitrogen™

The thiol-reactive biotin iodoacetamide reagent can be used to covalently attach biotin to thiol-containing proteins or thiolated nucleic acids.  The addition of a biotin residue enables the detection with avidin or streptavidin conjugates.  Electrophoretically separated thiol-containing proteins treated with biotin iodoacetamide have been detected in Western blots using an avidin–alkaline phosphatase conjugate.

DyLight™ 594 Maleimide Thermo Scientific™

Thermo Scientific DyLight 594 Sulfhydryl-Reactive Dye is a maleimide-activated derivative of high-performance DyLight 594 used to fluorescently label sulfhydryl-containing peptides, proteins and other biomolecular probes.

DyLight 594 provides vibrant orange-to-red fluorescence with better performance than other rhodamine derivatives including Alexa Fluor™ 594 and Texas Red™ dye for fluorescent applications over a broad pH range (pH 4-9). 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 594 Maleimide:

High performance—DyLight 594 shows brighter fluorescence than Alexa Fluor 594 and Texas Red
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 594 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.

Thiol and Sulfide Quantitation Kit Invitrogen™

The Thiol and Sulfide Quantitation Kit provides an ultrasensitive colorimetric assay for quantitating both protein and nonprotein thiols (also called sulfhydryls or mercaptans). In this assay, thiols or inorganic sulfides reduce a disulfide-inhibited derivative of papain, stoichiometrically releasing the active enzyme. The activity of the enzyme is then measured using the chromogenic papain substrate N-benzoyl-L-argining, p-nitroanilide (L-BAPNA). The enzymatic amplification step in this kit enables researchers to detect as little as 0.2 µM thiol - a sensitivity that is about 100-fold greater than that achieved using Ellman's reagent.
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