Radiosensitization of Anoxic Escherichia Coli Mutants by Diamide

Summary

The glutathione oxidant, diazenedicarboxylic acid bis (N, N′-diethylamide) (‘diamide’), sensitizes anoxic, but not euoxic, cells of several repair-deficient strains of Escherichia coli, but some strains are sensitized to a lesser extent than others. The degree to which each mutant is sensitized does not correlate in any obvious way with its oxygen enhancement ratio (o.e.r.) or with the absence of specific repair functions. Intracellular non-protein sulphydryl (NPSH) content of each strain is also unrelated to the o.e.r. Since the extent of NPSH oxidation by diamide is the same for all the strains, it does not account for the different degrees of sensitization. These results indicate that, at the level of cellular DNA, diamide enhances the effective yield of lethal lesions (e.g. strand breaks) and that the mechanism of action is at least partly different from that of oxygen.