Study of bioclusters of amino acids and peptides by mass spectrometry

The study of homo- and heterocluster quasimolecular ions of 20 L-amino acid s (A) and five dipeptides;by the TOF-PDMS method indicated that the intensi ty of quasimolecular ions of the corresponding homo-([A(n)+H](+) and [B-m+H ](+), where A and B are biomolecules (A, dipeptides), n and m=1....5) and h eteroclusters ([An Bm+H]+, n and m =1...5) depends mainly on the hydrophobi city of the constituents of the A cluster. The most intensive peaks of homo - and heterocluster ions were-obtained for hydrophobic amino acids: L-Ile, L-Leu, L-Val, and L-Phe, and for dipeptides containing these amino acids. T he assumption is made that the stereochemical parameters of heterocluster q uasimolecular ions in the TOF-PDMS method are determined by the physicochem ical mechanisms involved in the processes of ionization/desorption of biomo lecules and do not reflect directly biologically significant interactions o f biomolecules in vivo.