The catalytic mechanism of yeast thiosulfate reductase.

Thiosulfate reductase catalyzes the desulfuration of thiosulfonates while oxidizing GSH to GSSG. Kinetic studies of the enzyme-catalyzed reaction between GSH and benzenethiosulfonate have been carried out, and direct evidence for the occurrence of glutathione persulfide as an immediate product of the reaction has been obtained. The formal mechanism of this enzymic reaction has been shown to be rapid equilibrium-ordered with GSH as the leading substrate.