On the Nature of Intermolecular Interactions in Nucleic Acid Base−Amino Acid Side-Chain Complexes

• DOI: 10.1021/jp904146m
• Publication Date: 2009-07-28T12:46:38Z
• Authors: Ż. Czyżnikowska; P. Lipkowski; R. W. Góra; R. Zaleśny; A. C. Cheng
• Keywords: Side chain; Base (topology)

Twenty hydrogen-bonded complexes composed of nucleic acid base and amino side chain have been analyzed using ab initio quantum chemistry methods with the aim gaining insights into nature molecular interactions in these systems. The intermolecular interaction energies were estimated second-order Møller-Plesset perturbation theory coupled clusters approach single double excitations, while their components determined by means a hybrid variational-perturbational decomposition scheme. Additionally, topological analysis an electron density distribution studied has performed. In case all neutral complexes, main source stabilization is delocalizaction energy associated deformation upon which contributes almost half total energy. Furthermore, induced difference maps containing chains reveals that delocalization component involves changes localized double-hydrogen-bonded ring structures. A relatively good correlation between sum densities at hydrogen-bond critical points Hartree-Fock (electrostatic, delocalization, exchange) observed for two independently considered sets positively charged chains.