Gas-phase gradient optimization was carried out on the canonical Watson-Crick DNA base pairs using the second-order Moller-Plesset (MP2) perturbation method at the 6-31G* and 6-31G*(0.25) basis sets. It is detected that full geometry optimization at the MP2 level leads to an intrinsically nonplanar propeller-twisted and buckled geometry of G-C and A-T base pairs. Morokuma-Kitaura (MK) and reduced variational space (RVS) methods of the decomposition for molecular Hartree-Fock interaction energies were used for the investigation of the hydrogen bonding in the Watson-Crick base pairs in question. It is shown that the stability of the hydrogen-bonded DNA base pairs originates mainly from electrostatic interactions. At the same time the polarization, charge transfer and dispersion interactions also make considerable contribution to the attraction energy of bases.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)