LASER-DESORPTION IONIZATION MASS-SPECTROMETRY IN THE STUDY OF NATURALAND SYNTHETIC MELANINS .1. TYROSINE MELANINS

Nine synthetic, biosynthetic and natural tyrosine melanins, together w ith dopa and catechol melanins, have been studied by means of laser de sorption ionization mass spectrometry. The results obtained have shown that all the melanins under study consist of homogeneous sets of olig omers and have led to definitive information on their molecular weight distribution (from 500 to 30000 De). A deeper analysis of the spectra , in terms of mass differences among the various oligomers, allowed th e identification of some monomeric units, identical or analogous to th ose already proposed in the literature.