Radiation Sensitivity of DNA-metal Complexes: a Pulse Radiolysis Study.

The effect of silver(I) and mercury(II) complexing upon the rate of reaction of both the hydrated electron and the OH radical with DNA has been investigated using the technique of pulse radiolysis. The results presented do not support the hypothesis that the mechanism of radiation sensitivity by these metals is mediated through increased rate of free radical attack upon DNA. Also, there is evidence presented that neither metal, when complexed with DNA, reacts at a significant rate with the free radical species e-aq and OH. The technique of pulse radiolysis was also used to study the complexation of both silver(I) and mercury(II) with DNA (calf-thymus, 40 per cent GC). Scatchard plots, derived from the experimental data, gave association constants of 1.85 x 10(5) dm3 mol-1 and 9.9 x 10(4) dm3 mol-1 and n values (number of complexing sites per nucleotide) of 0.71 and 0.31 for silver(I) and mercury(II) respectively.