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DyLight 755 Sulfhydryl-Reactive Dye

Label cysteines with a bright alternative to Alexa Fluorâ„¢ 750 near-infrared dye.

DyLight 755 Sulfhydryl-Reactive Dye

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

DyLight 755 is a near-IR fluor that is invisible to the naked eye but increases the staining options when using infrared imaging systems. DyLight 755 has spectral properties that are very similar to other near-IR dyes, including Alexa Fluor™ 750. The high water solubility of DyLight Fluors means that a high dye-to-protein ratio can be attained without causing precipitation of the conjugates.


  • High performance – DyLight 755 replaces Alexa Fluor 755 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


  • 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

Product Details:

Fluorescent Western blot using DyLight 755 Infrared Western blot detection of ERK1 using DyLight 755-conjugated secondary antibody. Serial dilutions of A562 cell lysates were analyzed by Western blotting for levels of ERK1 using a mouse anti-ERK1 primary antibody and a goat anti-mouse secondary antibody conjugated to DyLight 755 (using the DyLight 755 Microscale Antibody Labeling Kit). Left lane: Infrared molecular weight marker.

DyLight 755 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.

Related Resources:

DyLight 755 Fluorophore Overview Page
Complete DyLight Fluor Product Guide

Related Products:

All DyLight Labeling Reagents and Kits
All Fluorescent Labeling Reagents and Kits
DyLight Fluor Secondary Antibody Conjugates
DyLight Fluor Streptavidin and NeutrAvidin Conjugates
Fluorescent Protein Stains

Ordering Information
Product # Description Pkg. Size Instructions MSDS CofA Price
62298 DyLight 755 Maleimide
Formulation: Maleimide activated proprietary near-infrared fluorescent dye
Sufficient For: 1 use to label a total of 7mg of IgG using typical conditions
1mg Product Instructions for product #62298 DyLight 755 Maleimide MSDS for product #62298 DyLight 755 Maleimide Certificate of Analysis for product #62298 DyLight 755 Maleimide $262.00

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Instructions | MSDS | CofA
Product Instructions | MSDS | CofA  

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