The Electronic Property Differences between dA::dG and dA::dG(oxo). A Theoretical Approach

The dA::dG(oxo) pair appearing in nucleic ds-DNA can lead to a mutation in the genetic information. Depending on the dG(oxo) source, an AT→GC and GC→AC transversion might be observed. As a result, glycosylases are developed during the evolution, i.e., OGG1 and MutY. While the former effectively removes G(oxo) from the genome, the second one removes adenine from the dA::dG(oxo) and dA:dG pair. However, dA::dG(oxo) is recognized by MutY as ~6–10 times faster than dA:dG. In this article, the structural and electronic properties of simple nucleoside pairs dA:dG, dC:::dG(oxo), dC:::dG, dA::dG(oxo) in the aqueous phase have been taken into theoretical consideration. The influence of solvent relaxation on the above is also discussed. It can be concluded that the dA::dG(oxo) nucleoside pair shows a lower ionization potential and higher electron affinity than the dA:dG pair in both a vertical and adiabatic mode. Therefore, it could be predicted, under electronic properties, that the electron ejected, for instance by a MutY 4[Fe-S](2+) cluster, is predisposed to trapping by the ds-DNA part containing the dA::dG(oxo) pair rather than by dA::dG.