Structure and Reactivity of Homocysteine Radical Cation in the Gas Phase Studied by Ion-Molecule Reactions and Infrared Multiple Photon Dissociation

TitleStructure and Reactivity of Homocysteine Radical Cation in the Gas Phase Studied by Ion-Molecule Reactions and Infrared Multiple Photon Dissociation
Publication TypeJournal Article
Year of Publication2013
AuthorsS. Osburn, T. Burgie, G. Berden, J. Oomens, R.AJ O'Hair, V. Ryzhov
JournalJournal of Physical Chemistry A
Volume117
Issue6
Pagination1144-1150
Date PublishedFeb
ISBN Number1089-5639
Abstract

The reactivity of the cysteine (Cys) and homocysteine (Hcy) radical cation was studied using ion molecule reactions. The radical cations were generated via collision-induced dissociation (CID) of their S-nitrosylated precursors. Cleavage of the S-NO bond led to the formation of the radical initially positioned on the sulfur atom. The reactions of the radical cations with dimethyl disulfide revealed that the cysteine radical cation reacts more quickly than the homocysteine radical cation. Infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory (DFT) calculations were used to determine the structure of the homocysteine radical cation, which was compared to the previously published structure of the cysteine radical cation (Sinha et al. Phys. Chem. Chem. Phys. 2010, 12, 9794-9800). IRMPD spectroscopy and DFT calculations revealed that this difference in radical reactivity was not a result of a radical rearrangement for the homocysteine radical cation but rather that the reactivity was modulated by stronger hydrogen bonding.

DOI10.1021/jp304769y
PID

e0c86893fa15318219ff51dc151b7171

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