Degradation of Nucleic Acid in Aqueous Solution by Ionizing Radiation

Summary

Experiments are described in which increasing concentrations of ammonium thymidylate, plus a variety of additional radical-scavenging compounds, are irradiated in aqueous solution with 250-kV X-rays. In addition to hydroxyl radicals, both hydrogen atoms and hydrated electrons can contribute to chromophore destruction. Under some conditions, where an excess of tert-butyl alcohol is present to scavenge hydroxyl radicals, up to 80 per cent of the observed chromophore damage can be attributed to the action of hydrated electrons. On average, about 65 per cent of the dTMP-hydroxyl radical interactions, 75 per cent of the dTMP-hydrogen atom interactions, and 67 per cent of the dTMP-hydrated electron interactions taking place under each set of experimental conditions resulted in chromophore destruction. The mathematical treatment of the data, on which these conclusions are based, is described.