Resistance of Coenzyme A to X-Irradiation

Abstract

In a report concerning the protective action of 0-mercaptoethylamine against radiation lethality, Bacq and associates (1) discussed possible mechanisms by which this chemical agent might exert its beneficial effect against radiation injury. These investigators called attention to the fact that 0-mercaptoethylamine is a constituent of the coenzyme A molecule and might exert a protective action on this coenzyme by competing for free radicals formed during irradiation. The sulfhydryl group of 3-mercaptoethylamine has been shown by Lynen and Reichert (2) to be the functional part of coenzyme A. Barron has stated (3) that coenzyme A is among the most sensitive sulfhydryl compounds toward oxidation by X-irradiation in vitro. Oxidation of the sulfhydryl groups of coenzyme A would prevent the normal transport of acyl groups as thioesters, and this defect should be reflected in a decreased ability of tissues of irradiated animals to perform acetylation reactions. The present study was undertaken to obtain information on the functional activity of coenzyme A in the tissues of irradiated animals. The influence of Xirradiation on acetylation reactions was measured by administering sulfanilamide to irradiated and normal rats and comparing urinary excretion of free and acetylated sulfanilamide.