HiLyte™ Fluor 647 C2 maleimide is an excellent thiol-reactive fluorescent labeling dye that generates the protein conjugates that are slightly red-shifted compared to those of Cy5 dyes, resulting in an optimal match to filters designed for Cy5 dyes. However, total fluorescence of the secondary antibody conjugates of HiLyte™ Fluor 647 dyes is significantly higher than that of Cy5 conjugates supplied by other companies. Also, unlike Cy5 dyes, HiLyte™ Fluor 647 dyes have very little change in absorption or fluorescence spectra when conjugated to most proteins, oligonucleotides and nucleic acids, thus yielding greater total fluorescence at the same degree of substitution. Additionally, our in-house data indicated that HiLyte™ Fluor 647 is superior to Cy5 in fluorescence polarization-based assays.Extinction Coefficient (M-1cm-1): 250,000Fluorescence quantum yield: 0.33Fluorescence Life Time (ns): 1.0