SEQUENTIAL KINETIC RESOLUTION BY 2 ENANTIOSELECTIVE ENZYMES

Enhancement of the enantioselectivity by simultaneous use of two enzym es in a sequential kinetic resolution process is presented. The model system consisted of carboxylesterase NP catalyzed hydrolysis of racemi c methyl 2-chloropropionate, followed by dehalogenation of the enantio merically enriched 2-chloropropionate by DL-dehalogenase into lactate. Optimal results are shown to be attained when the conversion rates of both faster reacting enantiomers are the same. An optimization parame ter D for sequential resolutions is introduced. The kinetics of both r eaction steps were investigated separately by progress curve analysis, and the enantioselectivity of the enzymes was determined. From a quan titative kinetic model we could formulate the sequential resolution, w hich yielded the predicted improvements of product enantiomeric excess .