Potential Repair of Free Radical Adducts of dGMP and dG by a Series of Reductants. A Pulse Radiolytic Study

Abstract

Using the technique of pulse radiolysis, it has been demonstrated that the interaction of hydroxyl-radical adducts of dG and dGMP with a series of reductants with different oxidation potentials at pH 7·0–7·4 proceeds via an electron transfer process (k ∼ 1·4–34 × 10⁸ dm³ mol⁻¹ s⁻¹). The one-electron oxidation of dGMP (dG) by Br^−·₂ was shown to result in the formation of a species, the properties of which are similar to those of the ·OH-radical adduct of dGMP with oxidizing properties based upon both spectral and kinetic information. The nature of the dGMP species produced on interaction with Br^−·₂ is discussed in terms of the ability of Br^−·₂ to produce specific base damage. The implications of these findings are presented in terms of potential free radical repair of hydroxyl radical damage and of synergistic effects whereby one reductant may be regenerated at the expense of another reductant.