DFT and Ab Initio Computational Study on the Reactivity Sites of the GABA and its Agonists, Such as CACA, TACA, DABA, and Muscimol: In the Gas Phase and Dielectric Media

The reactive behavior of GABA and its agonist molecules have been investigated using B3LYP hybrid density functional method at the 6-311++G** basis set level, in the gas phase and dielectric media. The calculations have been performed to obtain optimized geometries, relative energies, net atomic charges, HOMO, and LUMO energies. Solvent effects have been analyzed using isodensity polarized continuum model (IPCM) for four different solvents, which are chloroform, ethanol, DMSO, and H2O. The results have suggested that both the amino group and carboxyl group have been two of the most important active site for interactions between all compounds and their receptors. In addition they have suggested that the amino group reflects the difference in biological activity for each all molecules. The structures of these agonists have provided an essential foundation for subsequent structure-activity analysis of ligand binding at GABA receptors, neuronal uptake inhibitors and transporters. (C) 2010 Wiley Periodicals, Inc. Int J Quantum Chem 111: 3938-3948, 2011