Efficient synthesis of (R)-2-chloro-1-phenylethol using a yeast carbonyl reductase with broad substrate spectrum and 2-propanol as cosubstrate

In the screening of six Escherichia colt strains for overexpressing recombinant short-chain dehydrogenases/reductases from Yarrowia lipolytica ACA-DC 50109, an NADPH-dependent carbonyl reductase (YlCR) was identified with capability of producing chiral alcohols. The protein YlCR was over-expressed in E. colt BL21 (DE3), purified to homogeneity, and characterized of biocatalytic properties. The purified enzyme exhibited the highest activity at 35 degrees C and optimal pH at 7.0. The kinetic parameters K-m and K-cat of YlCR were 7.59 mM and 3.9 S-1 for a-chloroacetophenone, 366.1 mM and 2.94S(-1) for 2-propanol. YlCR showed a broad substrate spectrum toward aldehydes, ketones, alpha- and beta-keto esters. Among them, alpha-chloroacetophenone was found to be efficiently converted to (R)-2-chloro-1-phenylethol, the precursor for the synthesis of anti-depressants and a- or p-adrenergic drugs. Using 2-propanol as the hydrogen donor, a-chloroacetophenone (50 mM) was reduced with the recombinant E. coli, and the obtained conversation and enantiomeric excess (e.e) were both 99%. When the alpha-chloroacetophenone concentration was up to 200 mM, the conversion achieved 63%, and the e.e was always 99%. The present study serves as a valuable guidance for the future applications of this versatile biocatalyst. (C) 2015 Elsevier B.V. All rights reserved.