Oxidation of Glutathione by [FeIV(O)(N4Py)]2+: Characterization of an [FeIII(SG)(N4Py)]2+ Intermediate

The mechanism of glutathione (GSH) oxidation by a nonheme ferryl species has been investigated. The reaction of [FeIV(O)(N4Py)]2+ (1) with GSH in an aqueous solution leads to the rapid formation of a green intermediate, characterized as the low-spin ferric complex [FeIII(SG)(N4Py)]2+ (2) by UV−vis and electron paramagnetic resonance spectroscopies and by high-resolution time-of-flight mass spectrometry. Intermediate 2 decays to form the final products [FeII(OH2)(N4Py)]2+ and the disulfide GSSG over time. The overall reaction was fit to a three-step process involving rapid quenching of the ferryl by GSH, followed by the formation and decay of 2, which are both second-order processes.