New Approach for Fluorescent Peptide Labeling with Pyrylium Cyanine Dyes

New approach for fluorescent peptide labeling with cyanine dyes utilizing the reaction of pyrylium salts with aliphatic aminogroup is proposed. The reaction of two pyrylium cyanines dye acids was investigated. Lysocyme was used as a model peptide for conjugation. The proposed method can be used as a simple and convenient alternative for the known procedures because it does not require preparation of the unstable amino-reactive intermediates from a carboxyl- or sulfo-derivative of cyanine dyes.