Systematic Studies of the Methylation of DNA Base Molecules from First-principles

Abstract

We have studied selected DNA base molecules, such as guanine, cytosine, adenine, and thymine, and methylated DNA base molecules from first-principles. The impact of methylation and the rearrangement of the hydrogen atoms of the DNA base molecules on the geometries and the electronic properties are explained with the bond orders, the steric effects, and the molecular topologies. A DNA base molecule without methylation and a corresponding methylated DNA base molecule with the same bond order are expected to have similar HOMO-LUMO energy gaps.