γ-radiolysis of 2'-deoxyguanosine. The structure of the malondialdehyde-like product

In the γ-radiolysis of N2O/O2-saturated solutions of 2'-deoxyguanosine, 2'-deoxyguanosine-5'-aldehyde has been identified as the major product (G = 0.27) which gives rise to a positive 2-thiobarbituric acid test usually associated with malondialdehyde or structurally closely related compounds. From experiments with tetranitromethane as oxidant instead of oxygen it is concluded that the major primary precursor is not the radical at C(5') of the sugar moiety but a base radical. The relevance of these observations with respect to radiation-induced changes in DNA is discussed. (orig.)