Osburn Sandra, Berden Giel, Oomens Jos, Gulyuz Kerim, Polfer Nick C, O'Hair Richard A J, Ryzhov Victor
Department of Chemistry and Biochemistry, Center for Biochemical and Biophysical Studies, Northern Illinois University, Dekalb, IL 60115 (USA).
University Nijmegen, Institute for Molecules and Materials, FELIX Facility, Toernooiveld 7, 6525ED Nijmegen (The Netherlands).
Chempluschem. 2013 Sep;78(9):970-978. doi: 10.1002/cplu.201300057. Epub 2013 May 2.
A gas-phase radical rearrangement through intramolecular hydrogen-atom transfer (HAT) was studied in the glutathione radical cation, [γ-ECG] , which was generated by a homolytic cleavage of the protonated S-nitrosoglutathione. Ion-molecule reactions suggested that the radical migrates from the original sulfur position to one of the α-carbon atoms. Experiments on the radical cations of dipeptides derived from the glutathione sequence, [γ-EC] and [CG] , pointed to the glutamic acid α-carbon atom as the most likely site of the radical migration. Infrared multiple-photon dissociation (IRMPD) spectroscopy was employed to generate complementary information. IRMPD of [γ-ECG] in the approximately 1000-1800 cm region was inconclusive owing to the relatively broad, overlapping absorption bands. However, the IRMPD spectrum of [γ-EC] in this region was consistent with the radical migrating from the sulfur to the α-carbon atom of glutamic acid. IRMPD in the 2800-3700 cm region performed on [γ-ECG] is consistent with a mixture of both the original sulfur-based radical and the resulting glutamic acid α-carbon-based species. Comparisons are made with previously published condensed and gas-phase studies on intramolecular HAT in glutathione.
