Evidence for a common selenolate intermediate in the glutathione peroxidase-like catalysis of α-(phenylselenenyl) ketones and diphenyl diselenide

Article abstract of DOI:10.1016/S0040-4020(01)87004-6

The glutathione peroxidase-like catalysis of α-(phenylselenenyl) ketones was investigated. Degradation studies demonstrated the rapid cleavage of the aliphatic carbon-selenium bond of α-(phenylselenenyl) ketones by glutathione at pH 6.9 in a methanolic phosphate buffer under argon. On treatment with excess glutathione under aerobic conditions, α-(phenylselenenyl) ketones, S- (phenylselenenyl)glutathione and diphenyl diselenide were all shown to give benzeneselenolate. This material was found to be oxidized by hydrogen peroxide considerably faster than α-(phenylselenenyl) ketones, S- (phenylselenenyl)glutathione or diphenyl diselenide. A catalytic mechanism involving benzeneselenolate, benzeneselenenic acid and S- (phenylselenenyl)glutathione as crucial intermediates was proposed to account for the glutathione peroxidase-like catalysis of α-(phenylselenenyl) ketones and diphenyl diselenide.