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Conformation‐dependent intermolecular interaction energies of the triphosphate anion with divalent metal cations. Application to the ATP‐binding site of a binuclear bacterial enzyme. A parallel quantum chemical and polarizable molecular mechanics investigation
Author(s) -
Gresh Nohad,
Shi GenBin
Publication year - 2003
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.10312
Subject(s) - chemistry , intermolecular force , intramolecular force , interaction energy , polarizability , molecular mechanics , crystallography , divalent , stereochemistry , computational chemistry , molecular dynamics , molecule , organic chemistry
We have explored the conformation‐dependent interaction energy of the triphosphate moiety, a key constituent of ATP and GTP, with a closed‐shell divalent cation, Zn 2+ , used as a probe. This was done using the SIBFA polarizable molecular mechanics procedure. We have resorted to a previously developed approach in which triphosphate is built out from its elementary constitutive fragments, and the intramolecular, interfragment, interaction energies are computed simultaneously with their intermolecular interactions with the divalent cation. This approach has enabled reproduction of the values of the intermolecular interaction energies from ab initio quantum‐chemistry with relative errors <3%. It was extended to the complex of a nonhydrolyzable analog of ATP with the active site of a bacterial enzyme having two Mg 2+ cations as cofactors. We obtained following energy‐minimization a very close overlap of the ATP analog over its position from X‐ray crystallography. For models of the ATP analog–enzyme complex encompassing up to 169 atoms, the values of the SIBFA interaction energies were found to match their DFT counterparts with relative errors of <2%. © 2003 Wiley Periodicals, Inc. J Comput Chem 25: 160–168, 2004