Involvement of Hydroxyl Radicals in the Release by Ionizing Radiation of a Cell Surface Nuclease from Micrococcus radiodurans

Abstract

The ionizing radiation-induced release of a surface exonuclease from Micrococcus radiodurans is to a large extent inhibited by the removal of water. Irradiation of a cell suspension saturated with O$sub 2$ (an effective aqueous electron and hydrogen atom scavenger) allows the same release as irradiation in the presence of N$sub 2$. Ethanol (a good hydroxyl radical scavenger) protects the enzyme from release. These data suggest that hydroxyl radicals produced by the radiolysis of water are important releasing agents. Hydroxyl radicals produced by the ultraviolet decomposition of H$sub 2$O$sub 2$ were effective in releasing the enzyme. (auth)