Cy5 NHS Ester
A water-soluble Cy5 succinimidyl ester (SE, or NHS) is the most commonly used fluorescent labeling reagents for preparing far-red-fluorescent bioconjugates. Cy5 conjugates are bright, photostable, pH insensitive and produce minimal autofluorescence of biological specimens in this region of the spectrum. Water-soluble Cy5 dye can be used in place of Alexa Fluor® 647, DyLight® 649 and other dyes excitable at a wavelength of 633 or 647 nm.
This sulfonated dye is also known as sulfo-Cyanine5 NHS ester.
DyLight® and Alexa Fluor® are registered trademarks of Thermo Fisher Scientific. Cy®Dye is a trademark of GE Healthcare.
Cy5 dye (also sold under Sulfo-Cyanine5 name) is one of the most popular far-red fluorescent dyes. It is often a reagent of choice for protein and peptide labeling. Cy5 dye is a water-soluble, bright, far-red-fluorescent dye with excitation ideally suited for the 633 nm or 647 nm laser lines. Cy5 conjugates of antibodies, peptides, and proteins are pH insensitive from pH 4 to pH 10. A significant advantage to using long wavelength dyes such as Cy5 or AF 647 dye over other fluorophores is the low autofluorescence of biological specimens in this region of the spectrum.
The NHS ester (or succinimidyl ester) is the most popular amine reactive group for labeling with the primary amines of proteins (Lys), amine-modified oligonucleotides, and other amine-containing molecules. We do not recommend using Cy5 NHS ester for labeling proteins at high molar ration due significant self-quenching. Cy5 conjugates are recommended for detection of moderate-to-high abundance targets. For detection of low-abundance biological targets we recommend using AFDye 647 NHS Ester, which can be attached to proteins at high molar ratios without significant self-quenching, enabling brighter conjugates and more sensitive detection.
Cy5 spectrally is almost identical to Alexa Fluor® 647, CF® 647 Dye, or any other Cyanine5 based fluorescent dyes, and can be used as a less expensive alternative to Alexa Fluor® 647 NHS Ester.
DyLight® Alexa Fluor® is a registered trademark of Thermo Fisher Scientific. Cy®Dye is a trademark of GE Healthcare.