MECHANISM OF HYDROGEN SULFIDE FORMATION FROM THIOSULFATE

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Abstract
A crude enzyme prepara-tion from yeast which catalyzes the formation of hydrogen sulfide from thiosulfate and glutathione was studied. The protein fraction responsible for this catalysis was purified nearly fourfold. Sulfite and sulfide are the equimolar products formed in the reaction. When the reaction is coupled to glutathione reductase, sulfide is produced continuously from thiosulfate. Sulf ite was found to be a competitive inhibitor of the enzymatic reaction. Thiosulfate could reverse this inhibition. A mechanism similar to that proposed for rhodanese has been postulated for this reaction. The physiological significance of this hydrogen sulfide formation is discussed.