Thermal Annealment and Nitric Oxide Effects on Free Radicals in X-irradiated Cells

Abstract

Four kinds of radicals are identified in dry spores (Bacillus megaterium) after x-irradiation: those associated with singlet, doublet, triplet, and oxygen-complex types of spectra. The singlet, present only at low temperatures, gives rise irreversibly to the doublet at 25°C. All hyperfine structure is depressed after annealment at 1000°C and is lost when oxygen or nitric oxide is added. The physical results support the hypothesis that reactions of long-lived free radicals can account for the radiobiological phenomena of thermorestoration, nitric oxide protection, and latent oxygen effect.