MOLECULAR-STRUCTURE AND CONFORMATIONAL-ANALYSIS OF CHIRAL ALCOHOLS - APPLICATION TO THE ENANTIOSELECTIVITY STUDY OF LIPASES

The molecular structures of the chiral compounds 1-phenylethanol, 2-he xanol and 1-phenylethanol acetate have been studied theoretically by a b initio methods. Conformational analysis and electronic structure stu dies have been carried out with these molecules at STO-3G and 6-31G* basis sets. For the study of the interaction of lipases with substrate s, a simplified model of the tetrahedral intermediate has been calcula ted at the 6-31G//4-31G* level. Molecular mechanics simulations of th e interaction of these compounds with the lipases of Candida rugosa, P seudomonas cepacia and Rhizomucor miehei have been used to study the e nantioselectivity of these lipases in the transesterification reaction of the chiral alcohols. The theoretical results have been compared wi th experimental data and good agreement was observed. It can be conclu ded that the enantioselectivity of these lipases is controlled by the formation of a tetrahedral intermediate, whereas Michaelis complex for mation has a much lower significance.