Fluorescent dye that is water-soluble and forms stable peptide bond with protein amino groups. Fluorescent Dye 540-M may have less spillover effect than Pacific Orange due to its slightly sharper emission. All the Fluorescent Dye M series products are designed to be maximally excited by one of the major light sources equipped in flow cytometers. Besides, in comparison with phycobiliprotein tandems, Fluorescent Dye M series possesses better photostability, higher conjugation yields, and little pH sensitivity making it an ideal choice in fluorescence imaging applications.