Reduction of a trisulfide derivative of glutathione by glutathione reductase.

Glutathione trisulfide was synthesized from glutathione disulfide and its reduction by glutathione reductase was studied. A two-step reaction was observed. In a first step, the rate of reduction was similar to that observed with glutathione disulfide. In addition to glutathione, a persulfide intermediate was detected by an electrochemical method and was carboxymethylated by iodoacetate to be identified by Plasma Desorption Mass Spectrometry. During the second step the reduction of this intermediate led to the formation of hydrogen sulfide and a second equivalent of glutathione.