Hydroxyl radical reaction with the guanine-cytosine base pair: A density functional theory study

Abstract

To address problems such as aging, mutation, and cancer, it is of great importance to understand the damage mechanism of DNA induced by hydroxyl radical. In this study, the abstraction reaction mechanism of hydroxyl radical with guanine-cytosine (GC) base pair in aqueous phase under the polarized continuum model (PCM) has been explored by using density functional theory (DFT). The results indicated that all the abstraction reactions in GC base pair were thermodynamically exothermic, and the stability of dehydrogenation radicals decreased in the order of (H2b-GC)•>(GC-H4b)•>(GC-H6)•>(GC-H5)•~(H8-GC)•. The reaction energy of H2b abstraction pathway was the lowest among all investigated pathways, thus indicating that the reaction conversion of (H2b-GC)• was the highest. In the five hydrogen abstraction pathways, the local energy barriers with respect to the corresponding reactant complexes increased in the following order: H2b