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Rearrangements of doubly charged acylium ions from lysyl and ornithyl peptides
Author(s) -
Tang XueJun,
Boyd Robert K.
Publication year - 1994
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1290080903
Subject(s) - chemistry , peptide , residue (chemistry) , lysine , fragmentation (computing) , ion , ornithine , stereochemistry , mass spectrometry , amino acid , arginine , biochemistry , chromatography , organic chemistry , computer science , operating system
The study of large‐scale rearrangements of [b′] 2+ ions produced by electrospray ionization of Substance P (Tang et al., Anal. Chem. Vol. 65, p. 2824 (1993)) has been extended to 18 other peptides containing either a lysine or ornithine residue remote from the C‐terminus. Evidence for wholesale transfer of one or more residues, from the C‐terminus of the [b′] 2+ precursor to the ω‐amino group of the Lys (or Orn) residue, was observed for 12 of the 18 peptides studied. Unfortunately, no rigorous predictive rules, relating features of the peptide sequence to the propensity to undergo such rearrangements, could be discerned although a significant correlation with presence of a proline residue dose to the lysine or ornithine on the C‐terminal side was apparent. The resulting mass‐shifts can complicate derivation of peptide sequences from fragment‐ion spectra of [M+2H] 2+ peptide ions, for example, since the cyclized [b′] 2+ ions responsible for the rearrangements are readily formed as intermediate species in the fragmentation mechanisms.