THE ROLE OF ENZYMATIC OXYGEN REMOVAL IN CHEMICAL PROTECTION AGAINST X-RAY INACTIVATION OF BACTERIA

Abstract

Compounds found to be protective against the lethal action of X-rays on bacterial cells can be divided into 2 classes on the basis of whether or not pre-incubation with the cells was required for protection. A decrease in protective capacity was correlated with a decrease in respiration rate on those compounds which require pre-incubation for protection. Cells possessing an active hydrogenase system, exposed to X-rays in a H2-O2 mixture, were found to be more radioresistant than similar cells exposed in a N2-O2 mixture. Production of a highly reductive state in the cells and suspensions did not alter their radioresistance. The data presented are consistent with the hypothesis that O2 removal rather than H- donation is the major mode of protection afforded by chemical protective agents.