Purification and characterization of an aldehyde reductase from Candida magnoliae

An NADPH-dependent aldehyde reductase was purified to homogeneity from Candida magnoliae AKU4643 through four steps, including Blue-Sepharose affinity chromatography. The relative molecular mass of the enzyme was estimated to be 33,000 on high performance gel-permeation chromatography and 35,000 on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The substrate specificity of the enzyme was broad and resembled those of other aldo-keto reductases. The partial amino acid sequences of the enzyme showed that it belongs to the aldo-keto reductase superfamily. The enzyme catalyzed the stereoselective reduction of ethyl 4-chloro-3-oxobutanoate to the corresponding (R)-alcohol, with a 100% enantiomeric excess. The enzyme was inhibited by 1 mM quercetin, CuSO4 ZnSO4 and HgCl2. The thermostability of the enzyme was inferior to that of the (S)-CHBE-producing enzyme from the same strain. (C) 1999 Elsevier Science B.V. All rights reserved.