Open AccessInvestigation of the presence of b ions in electron capture dissociation mass spectra
Author(s) -
Helen J. Cooper
Publication year - 2005
Publication title -
journal of the american society for mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.961
H-Index - 127
eISSN - 1879-1123
pISSN - 1044-0305
DOI - 10.1016/j.jasms.2005.07.014
Subject(s) - chemistry , electron capture dissociation , fragmentation (computing) , ion , dissociation (chemistry) , mass spectrum , protonation , mass spectrometry , peptide , collision induced dissociation , electron ionization , amide , electron capture , analytical chemistry (journal) , stereochemistry , crystallography , tandem mass spectrometry , fourier transform ion cyclotron resonance , chromatography , organic chemistry , ionization , biochemistry , computer science , operating system
Previously, we have indicated (Cooper, H.J., et al. Int. J. Mass Spectrom., 2003, 228, 723-728) that electron capture dissociation (ECD) of the doubly protonated peptides, Leu(4)-Sar-Leu(3)-Lys-OH, Leu(4)-Ala-Leu(3)-Lys-OH, Gly(4)-Sar-Gly(3)-Lys-NH(2), and Gly(3)-Pro-Sar-Gly(3)-Lys-NH(2), results in abundant b ions, which derive from fragmentation of backbone amide bonds, a nonstandard fragmentation channel in ECD. The instrumental conditions were such that the possibility that collision-induced dissociation processes were contributing to the observed spectra was eliminated. In a separate study (Fung, Y.M.E., et al. Eur. J. Mass Spectrom., 2004, 10, 449-457. ECD of peptides Arg-(Gly)(n)-Xxx-(Gly)(n)-Arg, where Xxx is the amino acid of interest, did not result in b ions. The variation in ECD observed for strikingly similar peptides suggests that the nature of the charge carrier (Arg or Lys) is instrumental in governing the fragmentation channels. Here, we describe the ECD behavior of a suite of model peptides designed such that the nature and position of the charge carrier could be probed. The results suggest that the presence of b ions in ECD spectra is a consequence of both charge carrier and peptide structure. Possible mechanisms for the formation of b ions following electron capture are discussed.