The effect of radiation sensitizing and protective agents on the post-irradiation synthesis of DNA by membrane complexes of Escherichia coli B/r

SummaryMeasurements were made of the synthesis of DNA by membrane-DNA complexes extracted from Escherichia coli B/r that had been sensitized to or protected against the lethal effects of ionizing radiation by irradiating the bacteria in the presence of indane trione, acriflavine, thiourea, or β-mercaptoethanol. Pre-irradiation treatment of the bacteria with cuprous copper was also used as a method of sensitization. Acriflavine and β-mercaptoethanol interfered either with the lysis procedure for preparation of the membrane complex or with the DNA synthetic reaction itself. When agents were used which sensitize only in anoxic conditions (indane trione, copper compounds), there was no accompanying sensitization of the DNA-membrane system, but cells protected against cell-killing with thiourea, an agent which protects more effectively in aerated conditions of irradiation, yielded DNA-membrane complexes that were more resistant to radiation.