Properties of the thiobase pairs hydrogen bridges: a theoretical study.

The characteristics of the hydrogen bridges in the base pairs with S --> O substitution have been studied and the comparisons with the unmodified systems considered. The modifications induced by the sulfur atom in the structures, energies, and atomic charges have been evidenced and the energetic effects revaluated for the first time. Their effects on the hydrogen transfer from a base to the other and the relevance of these static and dynamical features for biological properties have been suggested.