title: Post-irradiation inactivation of the sulfhydryl enzyme malate synthase.
abstract: The sulfhydryl enzyme malate synthase was inactivated in air-saturated aqueous solution by X-irradiation (2 kGy). Changes of activity were registered up to 60 h after irradiation. Effects of specific additives (formate, superoxide dismutase, catalase), added before and/or after irradiation, revealed the role of the deleterious radical and non-radical species responsible for the radiation damage: inactivation during irradiation is mainly due to the action of OH, to a minor extent to O(2) and H2O2; post-irradiation inactivation is mainly caused by H2O2. A partial restoration of enzyme activity by dithiothreitol, added after irradiation, was found for all systems investigated; repairs were significant even when they were initiated 60 h after irradiation.
mesh_terms: D000818:Animals; D002374:Catalase / Q000378:metabolism; D002417:Cattle; D004912:Erythrocytes / Q000201:enzymology; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008292:Malate Synthase / Q000037:antagonists & inhibitors / Q000528:radiation effects*; D007652:Oxo-Acid-Lyases / Q000528:radiation effects*; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D013438:Sulfhydryl Compounds / Q000528:radiation effects; D013482:Superoxide Dismutase / Q000097:blood
chemical_list: D013438:Sulfhydryl Compounds; D002374:Catalase; D013482:Superoxide Dismutase; D008292:Malate Synthase; D007652:Oxo-Acid-Lyases