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SummaryThe transient absorption spectra produced on pulse radiolysis of aqueous solutions of DNA and related biochemicals, saturated with mixtures of nitrous oxide and oxygen, have been measured. Spectra observed immediately after the radiation pulse have been assigned to the respective adducts formed by the reaction of hydroxyl radicals. Except in the cases of 5-bromouracil, guanylic acid and DNA, the absorptions decayed rapidly and first order in oxygen. Absolute rate constants for the reaction of oxygen with the adducts of several pyrimidine bases have been determined and approach those of diffusion-controlled reactions. Analogous rates of reaction for the related nucleotides and nucleosides are approximately 50 per cent slower. Absolute rate constants for the reaction of oxygen with the hydroxy-adducts of tryptophan and histidine have also been determined.
R. L. Willson (Thu,) studied this question.