title: Theoretical Ab initio study of the effects of methylation on the nature of hydrogen bonding in A:T base pair.
abstract: We report the results of a theoretical ab initio study of methylation in Watson-Crick A:T base pairs. Equilibrium geometries were obtained without symmetry restrictions by the gradient procedure at DFT level of theory with the standard 6-31G(d) basis set. Each local minima was verified by energy second derivative calculations. Single-point calculations for the DFT geometries have been performed at the MP2/6-31G(d,p), MP2/6-31++G(d,p), and MP2/6-311++G(2d,2p) levels of theory. The geometrical parameters, relative stabilities and counterpoise corrected interaction energies are reported. In addition, using a variation-perturbation energy decomposition scheme, we have found the important contributions to the total interaction energy.
authors.affiliation: Computational Center for Molecular Structure and Interactions, Jackson State University, Jackson, MS 39217, USA.
authors.forename: Aviane
authors.initials: A
authors.lastname: Flood
authors.forename: Curinetha
authors.initials: C
authors.lastname: Hubbard
authors.forename: Gareth
authors.initials: G
authors.lastname: Forde
authors.forename: Glake
authors.initials: G
authors.lastname: Hill
authors.forename: Leonid
authors.initials: L
authors.lastname: Gorb
authors.forename: Jerzy
authors.initials: J
authors.lastname: Leszczynski
mesh_terms: D000225:Adenine / Q000737:chemistry*; D020029:Base Pairing; D019175:DNA Methylation; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008962:Models, Theoretical; D013941:Thymine / Q000737:chemistry*
chemical_list: D000225:Adenine; D013941:Thymine