Cy5 Amine is a carbonyl reactive building block used to modify carboxylic groups in the presence of activators (e.g. EDC, or DCC) or activated esters (e.g. NHS esters) through a stable amide bond. It also can be employed as a polar tracer and as a reactive dye for labeling proteins via a carboxylic acid moiety.
Cy5 Amine (also sold under the Sulfo-Cyanine5 Amine name) is a water-soluble, bright, far-red-fluorescent probe with excitation ideally suited for the 633 nm or 647 nm laser lines. 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.