title: Role of Coulomb energy in promoting collisionally activated dissociation of multiply charged peptides formed by electrospray ionization.
abstract: Electrospray ionization tandem quadrupole mass spectrometry has been applied to a series of lysine-substituted octaalanines and some naturally occurring peptides containing more than two basic amino acid residues. Unusually high fragmentation efficiency along with site-specific cleavages at the outer side of and remote from basic residues were observed for collisionally activated dissociation spectra of multiply charged peptides (MCP) with basic residues in close proximity. It was suggested that Coulomb energy (CE) rather than Coulomb repulsion (CR) was responsible for promoting fragmentation of the MCP studied. A possible fragmentation mechanism of MCP is proposed, in which the conversion of CE into internal vibrational energy was brought about by intramolecular proton migration in the presence of CR between charged sites.
authors.affiliation: National Institute of Materials and Chemical Research, Ibaraki, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ishikawa
authors.forename: T
authors.initials: T
authors.lastname: Nishimura
authors.forename: Y
authors.initials: Y
authors.lastname: Koga
authors.forename: Y
authors.initials: Y
authors.lastname: Niwa
mesh_terms: D000595:Amino Acid Sequence; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011522:Protons
chemical_list: D010455:Peptides; D011522:Protons