Fast Atom Bombardment and Tandem Mass Spectrometry for Sequencing Peptides and Polyamino Alcohols

Fast atom bombardment combined with collisional activation decomposition (CAD) spectrometry has been used to investigate eight peptides containing from three to six amino acids in order to derive some general conclusions about the CAD of the (M + H)+ of peptides. A scheme for interpreting the CAD spectra is developed and exemplified using a penta-peptide. The primary peptide backbone fragmentations give rise to N- and C-terminus-containing ions, resulting from peptide bond cleavage, and N-terminal-containing ions minus CO. In addition, the (M + H)+ Ions of polyamino alcohols, formed by chemical reduction of these peptides, were submitted to collisional activation. Complementary amino acid sequence-determining information is obtained. Moreover, the NH-CHj, cleavage, with charge retention on the C terminus, is now prominent for the reduced peptides. The potential of CAD spectrometry for studies of mixtures of peptides and mixtures of polyamino alcohols is demonstrated by analyzing an equimolar mixture of four peptides.