Water soluble, amino-reactive sulfo-Cyanine3 NHS ester. Efficiently labels proteins and peptides in purely aqueous solution, without need for organic co-solvent. Ideal for proteins with low solubility, and proteins prone to denaturation.This product is an analog of Cy3 NHS ester. Sulfo-Cyanine3 NHS ester replaces Cy3, Alexa Fluor 546, and DyLight 549 for all applications.