Like AMCA (7-amino-4-methyl coumarin-3-acetic acid), AMCA-X emits in the blue region (440-460 nm) upon activation with UV light (350 nm). The acid is readily activated to form succinimidyl ester that reacts with lysine residues under mild conditions to form photostable amide links. AMCA fluorophores have high fluorescence quantum yields with the emission wavelength that perfectly matchs the mercury lamp irradiation spectrum. These two characteristics allow photographic exposure time of AMCA-labeled sections to be reduced to a quarter of that required for a corresponding FITC conjugate. In general, AMCA-immunoglobulin conjugates are not susceptible to minimal photobleaching and have a storage life at -20 oC for more than two years.
Eis PS and Lakowicz JR (1993). Time-resolved energy transfer measurements of donor-acceptor distance distributions and intramolecular flexibility of a CCHH zinc finger peptide. Biochemistry 32, 7981-93; Khalfan H, et al. (1986). Aminomethyl coumarin acetic acid: a new fluorescent labeling agent for proteins. Histochem J 18, 497-9.