Kinetics of the Enzymatic Resolution of Racemic Compounds in Bi-Bi Reactions

Abstract

The course of the kinetic resolution of a racemic compound by an enantioselective enzyme can often be described using Michaelis-Menten kinetics. This description (Chen et at., 1982, 1987) is formally not correct for reactions with multiple substrates or products. Van Tol et at. (1992) showed for the lipase-catalyzed resolution of glycidyl butanoate that the ping-pong kinetic mechanism has to be taken into account. This paper systematically treats the deviations from the model of Chen that may occur for bi-bi reactions obeying ping-pong or ternary complex kinetics. The course of the enantiomeric excess as a function of the degree of conversion was found to be dependent on two or three kinetic parameters (in contrast to the single E-value of Chen), on the thermodynamic equilibrium constant and on the ratio of initial concentrations of the reactants. This ratio can be used to some extent to manipulate the enantiomeric excess in a resolution process.