Electrostatic potential maps of guanine, cytosine and the G-C base pair in the Watson-Crick and Hoogsteen configurations have been studied using a mapping dipole of length 1Åand strength 1 Debye. Net charges on the atoms of the molecules were obtained by the MNDO molecular orbital method. Several closest distances of approach (CDA) between the mapping dipole and atomic sites of the molecules were considered and potentials calculated using interactions of net charges keeping the dipole in the molecular plane in each case. While on one hand this work supports the existence of potential minima obtained by monopole isopotential mapping, on the other it yields additional useful information, e.g. electric field directions which correspond to the directions of probable hydrogen bonds with other species. A deep localized potential region is observed around N4 of cytosine in the Hoogsteen configuration while it is not present in the Watson-Crick base pairing.
Volume 134, 2022
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