Czyznikowska Z, Lipkowski P, Góra R W, Zaleśny R, Cheng A C
Theoretical Chemistry Group, Institute of Physical and Theoretical Chemistry, Wrocław University of Technology, Wyb. Wyspianskiego 27, 50-370 Wrocław, Poland.
J Phys Chem B. 2009 Aug 20;113(33):11511-20. doi: 10.1021/jp904146m.
Twenty hydrogen-bonded complexes composed of nucleic acid base and amino acid side chain have been analyzed using ab initio quantum chemistry methods with the aim of gaining insights into the nature of molecular interactions in these systems. The intermolecular interaction energies were estimated using the second-order Møller-Plesset perturbation theory and coupled clusters approach with single and double excitations, while their components have been determined by means of a hybrid variational-perturbational decomposition scheme. Additionally, the topological analysis of an electron density distribution of the studied complexes has been performed. In the case of all of the studied neutral complexes, the main source of stabilization is the delocalizaction energy associated with the electron density deformation upon the interaction which contributes almost half of the total interaction energy. Furthermore, analysis of the interaction induced difference density maps of complexes containing neutral amino acid side chains reveals that the delocalization component involves the electron density changes localized in the double-hydrogen-bonded ring structures. A relatively good correlation between the sum of densities at hydrogen-bond critical points and the Hartree-Fock intermolecular interaction energy components (electrostatic, delocalization, and exchange) has been observed for the two independently considered sets of complexes, containing positively charged and neutral amino acid side chains.
利用从头算量子化学方法分析了由核酸碱基和氨基酸侧链组成的20种氢键复合物，目的是深入了解这些体系中分子相互作用的本质。使用二阶Møller-Plesset微扰理论和含单双激发的耦合簇方法估算分子间相互作用能，同时通过混合变分-微扰分解方案确定其组成部分。此外，还对所研究复合物的电子密度分布进行了拓扑分析。在所有研究的中性复合物中，稳定化的主要来源是与相互作用时电子密度变形相关的离域能，它几乎占总相互作用能的一半。此外，对含有中性氨基酸侧链的复合物的相互作用诱导差分密度图的分析表明，离域成分涉及双氢键环结构中局部的电子密度变化。对于两组独立考虑的复合物，即含有带正电和中性氨基酸侧链的复合物，已观察到氢键临界点处密度总和与Hartree-Fock分子间相互作用能成分（静电、离域和交换）之间存在相对良好的相关性。
