title: Glutathione radical cation in the gas phase; generation, structure and fragmentation.
abstract: Two different chemical methods have been used to form glutathione radical cations: (1) collision-induced dissociations (CIDs) of the ternary complex [Cu(II)(tpy)(M)]˙(2+) (M = GSH, tpy = 2,2':6',2''-terpyridine) and (2) homolysis of the S-NO bond in protonated S-nitrosoglutathione. The radical cations, M˙(+), were trapped and additional CIDs were performed. They gave virtually identical CID spectra, suggesting a facile interconversion between initial structures prior to fragmentation. DFT calculations at the B3LYP/6-31++G(d,p) level of theory have been used to study interconversion between different isomers of the glutathione radical cation and to examine mechanisms by which these ions fragment. The N-terminal α-carbon-centred radical cation, strongly stabilized by the captodative effect, is at the global minimum, which is 8.5 kcal mol(-1) lower in enthalpy than the lowest energy conformer of the S-centred radical cation. The barrier against interconversion is 18.1 kcal mol(-1) above the S-centred radical.
authors: Department of Chemistry and Centre for Research in Mass Spectrometry, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3.
authors: Junfang
authors: J
authors: Zhao
authors: K W Michael
authors: KW
authors: Siu
authors: Alan C
authors: AC
authors: Hopkinson
mesh_terms: D002412:Cations / Q000138:chemical synthesis / Q000737:chemistry; D005609:Free Radicals / Q000138:chemical synthesis / Q000737:chemistry; D005740:Gases / Q000138:chemical synthesis / Q000737:chemistry; D005978:Glutathione / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D011789:Quantum Theory; D013237:Stereoisomerism
chemical_list: D002412:Cations; D005609:Free Radicals; D005740:Gases; D005978:Glutathione