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DyLight 350 Sulfhydryl-Reactive Dye

Label cysteines with a bright alternative to Alexa Fluorâ„¢ 350 and AMCA dyes.

DyLight 350 Sulfhydryl-Reactive Dye

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.


  • 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


  • 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:

Fluorescence detection of DyLight 350 dye
Immunofluorescence microscopy using DyLight 350 dye. Alpha-tubulin (blue) and Lamin B1 (green) in A549 cells were fluorescently labeled with their respective primary antibodies and DyLight 350-Conjugated Highly Cross-Adsorbed Goat Anti-Mouse or DyLight 488-Conjugated Goat Anti-Rabbit Secondary Antibodies, respectively.

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.

Related Resources:

DyLight 350 Fluorophore Overview Page
Complete DyLight Fluor Product Guide

Related Products:

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

Ordering Information
Product # Description Pkg. Size Instructions MSDS CofA Price
46622 DyLight 350 Maleimide
Formulation: Maleimide activated proprietary blue fluorescent dye
Sufficient For: 1 use to label a total of 8mg of IgG using typical conditions
1mg Product Instructions for product #46622 DyLight 350 Maleimide MSDS for product #46622 DyLight 350 Maleimide Certificate of Analysis for product #46622 DyLight 350 Maleimide $262.00

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Instructions | MSDS | CofA
Product Instructions | MSDS | CofA  

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