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Molecular orbital calculations of metal ion interaction with nucleic acid bases. I. Binding of Cu(II) with adenine, guanine, uracil, and cytosine
Author(s) -
Kothekar V.,
Dutta S.
Publication year - 1977
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560120309
Subject(s) - guanine , uracil , chemistry , nucleic acid , cytosine , crystallography , binding energy , natural bond orbital , ion , molecular orbital , dna , stereochemistry , computational chemistry , molecule , atomic physics , density functional theory , nucleotide , organic chemistry , biochemistry , physics , gene
The reaction of the transition metal ion Cu(II) with nucleic acid bases—adenine, guanine, uracil, and cytosine—has been investigated by conformation energy calculations ( CEC ) and molecular orbital ( MO ) methods. Various binding sites, e.g., N 7 –C 6 NH 2 , N 7 –C 6 O, N 3 ‐N 9 , and N 1 in purines and N 3 and O 8 in pyramidines, have been considered. It was found that the energy minima for different binding sites had different values. In addition to the energy minima in the nucleic acid base plane, we have observed out‐of‐plane energy minima, differing in energy by a few kcal/mol in most of the cases. The MO calculations were performed on the most favorable planar positions obtained. It was found that the presence of Cu(II) alters the charge distribution pattern of practically all the atoms of nucleic acid bases. Its main effect is to withdraw electrons from the negatively charged nitrogens and positively charged carbons. The oxygen charge did not alter significantly. The results are compared with the experimental electron spin resonance and x‐ray diffraction studies and their biological significance is discussed.