title: Highly stereoselective reduction of prochiral ketones by a bacterial reductase coupled with cofactor regeneration.
abstract: A carbonyl reductase gene (yueD) from Bacillus sp. ECU0013 was heterologously overexpressed in Escherichia coli, and the encoded protein (BYueD) was purified to homogeneity and characterized. The NADPH-dependent reductase showed a broad substrate spectrum towards different aromatic ketones, and α- and β-ketoesters. Although the enantioselectivity was high to moderate for the reduction of α-ketoesters, all the tested β-ketoesters and aromatic ketones were reduced to the corresponding chiral alcohols in enantiomerically pure forms. Furthermore, the practical applicability of this enzyme was evaluated for the reduction of ethyl 4-chloro-3-oxobutanoate (1a). Using Escherichia coli cells coexpressing BYueD and glucose dehydrogenase, 215 g L(-1) (1.3 M) of 1a was stoichiometrically converted to ethyl (R)-4-chloro-3-hydroxybutanoate ((R)-1b) in an aqueous-toluene biphasic system by using a substrate fed-batch strategy, resulting in an overall hydroxyl product yield of 91.7% with enantiomeric purity of 99.6% ee.
authors.affiliation: Laboratory of Biocatalysis and Synthetic Biotechnology, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Ni
authors.forename: Chun-Xiu
authors.initials: CX
authors.lastname: Li
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Jian-He
authors.initials: JH
authors.lastname: Xu
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005948:Glucose Dehydrogenases / Q000378:metabolism* / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007659:Ketones / Q000737:chemistry*; D010084:Oxidation-Reduction; D013237:Stereoisomerism; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D007659:Ketones; D000429:Alcohol Oxidoreductases; D005948:Glucose Dehydrogenases