Sulfhydryl Factors in Degradation of lnsulin-l131 by Liver Extracts.

Abstract

The activity of a heat labile, probably proteolytic, enzyme system of rat liver was inhibited by p-chloromercuribenzoic acid and enhanced by the addition of glutathione. Glutathione itself can degrade insulin-I131 and render it more soluble in trichloroacetic acid. Electrophoretic studies suggest that this involves reduction of the insulin molecule rather than direct deiodination. Rat liver extracts also contain a heat stable factor which can degrade insulin-I131, and this activity appears to depend upon the presence of sulfhydryl compounds. Thus, the degradation of insulin by rat liver may involve reductive as well as proteolytic factors.