1 research outputs found
Heterolytic NâC<sub>α</sub> Bond Cleavage in Electron Capture and Transfer Dissociation of Peptide Cations
Mass spectrometry techniques employing electron capture
and electron
transfer dissociation represent powerful approaches for the analysis
of biological samples. Despite routine employment in analytical fields,
the underlying physical processes dictating peptide fragmentation
remain less understood. Among the most accepted mechanisms, the Cornell
proposal of McLafferty postulates that the homolytic cleavage of NâC<sub>α</sub> bonds located in the peptide backbone occurs on the
right (C-terminal) side of a hydrogen acceptor carbonyl group. Here,
we illustrate that an alternative âenolâ mechanism,
based on a heterolytic NâC<sub>α</sub> bond cleavage
located on the left (N-terminal) side of an acceptor carbonyl group,
not only is thermodynamically viable but also often represents the
energetically preferred cleavage route