A SIMPLE METHOD TO DETERMINE THE ENANTIOMERIC RATIO IN ENANTIOSELECTIVE BIOCATALYSIS

The enantiomeric ratio (E) is commonly used to characterize the enanti oselectivity in enzyme-catalyzed kinetic resolution. In this paper thi s parameter is directly derived from the enantiomeric excess of substr ate and product. This is formally more correct than using Chen's equat ion after calculating the degree of conversion from both ee values usi ng the relation of Sih and Wu. New expressions and useful graphs have been generated for reversible and irreversible uni-uni reactions. The theoretical predictions have been verified experimentally for various reactions. Values for E and the thermodynamic equilibrium constant, K( EQ), were obtained for a (DL)-dehalogenase-catalyzed dehalogenation, a hydrolysis reaction by porcine pancreatic lipase, and for C. Cylindra cea lipase-catalyzed esterification and transesterification. In view o f the current developments in the field of chiral analysis, this metho d is an easily available tool in the quantitative treatment of enzyme- catalyzed resolution of enantiomers.