Oxidative DNA damage induced by autoxidation of microquantities of S(iv) in the presence of Ni(ii)–Gly-Gly-His

Abstract

Ni^IIGGH (GGH = glycylglycylhistidine) reacts rapidly with S(IV), in air-saturated solution, to produce Ni^IIIGGH. A mechanism is proposed where initial Ni^III oxidizes SO₃²⁻ to SO₃˙⁻, which reacts with dissolved oxygen to produce SO₅˙⁻, initiating radical chain reactions. DNA strand breaks and 8-oxo-7,8-dihydro-2′-deoxyguanosine formation were observed in air-saturated solutions containing micromolar concentrations of Ni(II) and S(IV). The extent of DNA damage showed dependence on the ratio of the Ni^IIGGH : S(IV) concentrations and the ionic strength.