A kinetic study and application of a novel carbonyl reductase isolated from rhodococcus erythropolis

Abstract

The newly described carbonyl reductase from Rhodococcus erythropolis ( RECR) accepts a broad range of substrates. Based on the kinetic constants of a variety of methyl and ethyl ketones a hypothetical model of the substrate-binding site is proposed. Whether a substrate of interest may be reduced by the RECR can be predicted from this model together with the kinetic data. A study of initial velocities and product inhibition is presented, which shows that the kinetics of the RECR follow a Theorell-Chance mechanism. The pro- R hydride of NADH is transferred by the enzyme to the re face of the carbonyl compounds yielding ( S)-alcohols. The reduction of methyl 3-oxobutanoate and ethyl 4-chloro-3-oxobutanoate catalyzed by the oxidoreductase lead to the corresponding hydroxy compounds with high enantiomeric purity [enantiomeric excess ( e.e.) ≥ 99 %]. The synthesis of ethyl (2 R,3 S)-3-hydroxy-2-methylbutanoate was accomplished with high diastereoselectivity (diastereomeric excess = 95 %) and enantioselectivity ( e.e. ≥ 95 %).