Size-expanded DNA bases: An ab initio study of their structural and electronic properties

Second-order Moller-Plesset perturbation theory and density functional theory (DFT) are used to investigate the structural and electronic properties of size-expanded DNA bases, xA, xC, xG, and xT, and their natural counterparts. The results show that natural and size-expanded bases have both nonplanar amino groups, but the latter also has nonplanar aromatic rings, and xG is easier to oxidize than G.