The Mechanism of Action of AET: VI. The Protection of Proteins against Ionizing Radiation by GED

Abstract

The mechanism of action of the radiation-protective agent GED [bis-2-(guanidoethyl)disulfide] was studied in protein solutions. to 1% solutions of trypsin, lysozyme, and aldolase, GED (5 x 10-4 [image]) provided significant protection against inactlvation and solubility changes. This protection was not the result of scavenging of radicals from the radiolysis of water. Such scavenging appeared to occur only in solutions containing less than 1% protein. The only change in GED during irradiation of solutions containing 1% or more protein was protein binding. This binding was always by mixed disulfide formation in proteins containing sulfhydryl or disulfide groups. The mechanism of protection by radiation-induced mixed disulfide formation between GED and protein sulfur groups is postulated, and it is suggested that this may be a mechanism of protection in the living animal.