Theoretical study on the hydrolytic deamination reaction mechanism of guanine and (H2O)n

The hydrolytic deamination reaction mechanism of guanine (G) and (H2O)n (n = 1–4) has been theoretically investigated, including solvent effects at the B3LYP/6-31G (d,p) and MP2/6-311G (d,p) levels. The results show that the hydrolytic deamination reaction of G involves two steps. In the first step, a tetra-coordinated intermediate is generated by a hydrolysis reaction, and then deamination reaction is carried out. In the second step, the final products form via a hydrogen transfer. For the hydrolytic deamination reaction of guanine and 3H2O or 4H2O, only two molecules of water participate in the reaction, and other water molecule make the transition state more stable as a catalyst. The study on the potential energy surface shows that the deamination reaction of G and nH2O does not take place because of a higher barrier for the opening system, which is in agreement with the experimental result.