PROBING THE ACTIVE CONFORMERS OF PARAOXON THROUGH THEORETICAL CONFORMATIONAL STUDIES

Theoretical conformational studies have been carried out at the density functional (DFT) level of theory on paraoxon (O,O-diethyl-O-p-nitrophenylphosphonate) to correlate its conformational and enzyme inhibition properties. The aqueous solvation of the various conformers has been studied at the DFT level using polarized continuum model with conductor-like solvation approach. The results show that paraoxon has high conformational flexibility in aqueous medium, although in gas phase the molecule is less flexible. The barriers to transition to different low-energy conformers in aqueous medium are thermally accessible. The molecular electrostatic potential surfaces of the various low-energy conformers of this molecule have been compared with the related enzyme-bound organophosphorus structures to investigate the role of the calculated conformers on the biological activity of this molecule.