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.
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, Zn2+, 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 Mg2+ 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%.
Gresh
Nohad
N
Laboratoire de Pharmacochimie Moléculaire et Structurale, FRE 2463 CNRS, U266 INSERM, Université René-Descartes, 4, Avenue de l'Observatoire, 75006, Paris, France. gresh@biomedicale.univ-paris5.fr
Shi
Gen-Bin
GB
D000255:Adenosine Triphosphate / Q000737:chemistry*; D001665:Binding Sites; D006160:Guanosine Triphosphate / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D011487:Protein Conformation; D013816:Thermodynamics; D013820:Thermolysin / Q000737:chemistry*; D001618:beta-Lactamases / Q000737:chemistry*
D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D013820:Thermolysin; D001618:beta-Lactamases