Hydrogen Atom Abstraction Reactions of the Sugar Moiety of 2′-Deoxyguanosine with an OH Radical: A Quantum Chemical Study

Mechanisms of hydrogen atom abstraction reactions of the sugar moiety of 2'-deoxyguanosine with an OH radical were investigated using the B3LYP and BHandHLYP functionals of density functional theory and the second order Moller-Plesset Perturbation (MP2) theory in gas phase and aqueous media. The 6-31+G* and AUG-cc-pVDZ basis sets were used. Gibbs free barrier energies and rate constants of the reactions in aqueous media suggest that an OH radical would abstract the hydrogen atoms of the sugar moiety of 2'-deoxyguanosine in the following order of preference: H5' approximate to H5 '' > H3' > H4' > H1' approximate to H2' > H2 '', the rate constant for H5' abstraction being 10(3)-10(5) times greater than that for H2 '' at the different levels of theory. Relative stabilities of the different deoxyribose radicals are also discussed. The most and least favored hydrogen abstraction reactions found here are in agreement with experimental observation. (C) 2010 Wiley Periodicals, Inc. Int J Quantum Chem 111: 2160-2169, 2011