PNNL

Abstract

Comparison between gas-phase fragmentation of odd-electron M+• and [M-2H]-• ions of model peptides reported in this study demonstrates that charge-remote radical-driven fragmentation pathways play an important role in dissociation of odd-electron peptide ions. We found that charge-remote processes are responsible for a variety of side chain losses from the precursor ion and some backbone fragmentation. These fragmentation pathways most likely involve hydrogen abstraction from the ß-carbon of the side chain by the radical site that initiates subsequent cleavages. The results reported in this work are generally relevant for understanding of fragmentation patterns of odd-electron peptide ions produced by different approaches including capture of low-energy electrons, electron detachment and electron transfer.