Double-Ionization damage to guanine nucleotide

Computations were carried out to investigate the mechanism of double-ionization damage for deoxyguanosine nucleotide. The results reveal that the polarization of the water environment reduces double-ionization energies and facilitates the hole transfer. Double ionization in solutions is independent of the counterion. The environment screens the contribution of the phosphate group. After double ionization, cleavage of the C-N glycosidic bond is a barrierless process in the gas phase. The barrier height of bond break is ∼ 4.0 kcal/mol in solutions. The C-N scission could be a potential damaged pathway. The counterion has a minor effect on the bond rupture.