Peptide studies using a fast atom bombardment high field mass spectrometer and data system. 4. Disulfide-containing peptides.

Ten peptides containing one, two or three disulfides were examined to determine their behavior under fast atom bombardment (FAB) mass spectrometric conditions. The mass spectra for the disulfide and the reduced disulfide forms of each peptide were compared. Several factors were examined that contribute to the fast atom bombardment mass spectra of these peptides: components of the FAB matrix such as alkali cations, acids, bases and reducing agents, the intrinsic molecular properties of the intact peptide, and the effect of reducing conditions on sensitivity. The FAB mass spectra of the disulfide-containing peptides examined in this study displayed accurate molecular weight information and fragmentation which indicated the position of the disulfide in the amino acid sequence.