| Title | S-to-alpha C Radical Migration in the Radical Cations of Gly-Cys and Cys-Gly |
| Publication Type | Journal Article |
| Year of Publication | 2012 |
| Authors | Osburn S, Berden G, Oomens J, O'Hair RAJ, Ryzhov V |
| Journal | Journal of the American Society for Mass Spectrometry |
| Volume | 23 |
| Pagination | 1019-1023 |
| Date Published | Jun |
| Type of Article | Article |
| ISBN Number | 1044-0305 |
| Accession Number | WOS:000303685800004 |
| Keywords | calculations, CLEAVAGE, Cysteine, Damage, DFT, dissociation, FACILITY, GAS-PHASE, GENERATION, Hydrogen atom transfer, ion-molecule reactions, IRMPD SPECTROSCOPY, MECHANISMS, PEPTIDE RADICALS, PROTEIN, RADICAL CATIONS, Radical migration |
| Abstract | The radical cations of Cys-Gly and Gly-Cys were studied using ion-molecule reactions (IMR), infrared multiple-photon dissociation (IRMPD) spectroscopy, and density functional theory (DFT) calculations. Homolytic cleavage of the S-NO bond of nitrosylated precursors generated radical cations with the radical site initially located on the sulfur atom. Time-resolved ion-molecule reactions showed that radical site migration via hydrogen atom transfer (HAT) occurred much more quickly in Gly-Cys(aEuro cent+) than in Cys-Gly(aEuro cent+). IRMPD and DFT calculations indicated that for Gly-Cys, the radical migrated from the sulfur atom to the alpha-carbon of glycine, which is lower in energy than the sulfur radical (-53.5 kJ/mol). This migration does not occur for Cys-Gly because the glycine alpha-carbon is higher in energy than the sulfur radical (10.3 kJ/mol). DFT calculations showed that the highest energy barriers for rearrangement are 68.2 kJ/mol for Gly-Cys and 133.8 kJ/mol for Cys-Gly, which is in agreement with both the IMR and IRMPD data and explains the HAT in Gly-Cys. |
| URL | http://gateway.isiknowledge.com/gateway/Gateway.cgi?&GWVersion=2&SrcAuth=Test&SrcApp=TestApp&DestLinkType=FullRecord&KeyUT=WOS:000303685800004&DestApp=WOS |
| Department | GUTHz |
| Alternate Journal | J. Am. Soc. Mass Spectrom. |
