Influence of thiols and oxygen on the survival of γ-irradiated plasmid DNA and cells

Abstract

Some of the recent progress made in the understanding of the quantitative aspects of the oxygen effect in radiation biology by several groups is summarized. Examples are: the importance of unrepairable damage for the quantitative description of the oxygen effect; proof that protein thiols hardly contribute to protection in cells in the absence of oxygen; the proposal that protection by thiols in concentration ranges where al DNA radicals react with oxygen is due to the formation of hydroperoxides which can be repaired enzymatically by glutathione peroxydase; the finding that unscavengeable damage in plasmid DNA is mainly due to spur-induced clustered damages, but that the precursors of the scavengeable and the unscavengeable damage are comparably well repaired by thiols; the result that E. coli repair wild type strains are better protected by addition of thiols than strains with deficiencies in enzymatic repair capacities.