The Role of Aromaticity, Hybridization, Electrostatics, and Covalency in Resonance‐Assisted Hydrogen Bonds of Adenine–Thymine (AT) Base Pairs and Their Mimics

ChemistryOpen

L. Guillaumes¹  Dr. S. Simon¹ 

[1] Institut de Química Computacional i Catàlisi, Departament de Química, Universitat de Girona, Girona, Spain)

关键词: aromaticity;    density functional calculations;    DNA base pairs;    molecular orbital (MO) theory;    nucleotides;    resonance-assisted hydrogen bonding;   

DOI  :  10.1002/open.201402132

来源: Wiley

【 摘 要 】

Abstract

Hydrogen bonds play a crucial role in many biochemical processes and in supramolecular chemistry. In this study, we show quantum chemically that neither aromaticity nor other forms of π assistance are responsible for the enhanced stability of the hydrogen bonds in adenine–thymine (AT) DNA base pairs. This follows from extensive bonding analyses of AT and smaller analogs thereof, based on dispersion-corrected density functional theory (DFT). Removing the aromatic rings of either A or T has no effect on the Watson–Crick bond strength. Only when the smaller mimics become saturated, that is, when the hydrogen-bond acceptor and donor groups go from sp² to sp³, does the stability of the resulting model complexes suddenly drop. Bonding analyses based on quantitative Kohn–Sham molecular orbital theory and corresponding energy decomposition analyses (EDA) show that the stronger hydrogen bonds in the unsaturated model complexes and in AT stem from stronger electrostatic interactions as well as enhanced donor–acceptor interactions in the σ-electron system, with the covalency being responsible for shortening the hydrogen bonds in these dimers.

【 授权许可】

CC BY-NC-ND   
© 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

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