主题：【已应助】New Insights into the Vacuum UV Photodissociation of Peptides

Ramakrishnan Parthasarathi, Yi He, James P. Reilly
and Krishnan Raghavachari*
Department of Chemistry, Indiana University,
Bloomington, Indiana 47405
J. Am. Chem. Soc., 2010, 132 (5), pp 1606–1610
DOI: 10.1021/ja907975v
Publication Date (Web): January 15, 2010
Copyright © 2010 American Chemical Society

Vacuum ultraviolet laser photodissociation (UVPD) of peptide ions leads to unusual
dissociation channels involving backbone C−C bond breaking. However, the molecular basis for
the observed behavior is not clearly understood. We now report theoretical investigations
using ab initio/density functional theory (DFT) techniques on neutral and protonated
dipeptides undergoing vacuum ultraviolet (VUV) induced fragmentation via a Rydberg
excitation (and/or electron detachment) and subsequent C−C bond cleavage. New
experimental results on VUV photodissociation of dipeptides (protonated Ala_Arg and Arg_Ala)
provide strong support for our proposed model. Our mechanism also provides a natural
explanation for the presence of immonium ions that are sometimes observed in such
experiments.

http://pubs.acs.org/doi/pdfplus/10.1021/ja907975v