Studies on Radiolysis of Amino Acids and Proteins I. On Radiolytic Oxidation of Sulfhydryl Groups

Abstract

By relatively small doses of γ-irradiation, inactivation of sulfhydryl enzymes such as alcohol dehydrogenase and urease, were proved to be induced. This inactivation was recovered reversibly by the addition of thiol compounds such as cysteine and glutathione.
In the course of radiolysis of cysteine, measurable decrease in the amount of sulfhydryl group was found to occur by the small doses of the irradiation and, of course, by large irradiation doses. Such decrease in the amounts of sulfydryl group was found to occur also on the sulfhydryl enzyme proteins. Moreover, the lost activities in the inactivation of the enzymes was proved to be corresponding to the decrease of the sulfhydryl groups. A valid evidence, thus, was added to the mechanism of inactivation of sulfhydryl enzymes by ionizing radiation.