Open AccessFragmentation of α-radical cations of arginine-containing peptides
Author(s) -
Julia Laskin,
Zhibo Yang,
Chi-On Ng,
Ivan K. Chu
Publication year - 2010
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.2009.12.021
Subject(s) - chemistry , fragmentation (computing) , radical , electron capture dissociation , radical ion , side chain , dissociation (chemistry) , collision induced dissociation , ion , hydrogen atom abstraction , photochemistry , crystallography , tandem mass spectrometry , mass spectrometry , organic chemistry , fourier transform ion cyclotron resonance , polymer , chromatography , computer science , operating system
Fragmentation pathways of peptide radical cations, M(+*), with well-defined initial location of the radical site were explored using collision-induced dissociation (CID) experiments. Peptide radical cations were produced by gas-phase fragmentation of Co(III)(salen)-peptide complexes [salen = N,N'-ethylenebis (salicylideneiminato)]. Subsequent hydrogen abstraction from the beta-carbon of the side-chain followed by C(alpha)-C(beta) bond cleavage results in the loss of a neutral side chain and formation of an alpha-radical cation with the radical site localized on the alpha-carbon of the backbone. Similar CID spectra dominated by radical-driven dissociation products were obtained for a number of arginine-containing alpha-radicals, suggesting that for these systems radical migration precedes fragmentation. In contrast, proton-driven fragmentation dominates CID spectra of alpha-radicals produced via the loss of the arginine side chain. Radical-driven fragmentation of large M(+*) peptide radical cations is dominated by side-chain losses, formation of even-electron a-ions and odd-electron x-ions resulting from C(alpha)-C bond cleavages, formation of odd-electron z-ions, and loss of the N-terminal residue. In contrast, charge-driven fragmentation produces even-electron y-ions and odd-electron b-ions.