Biocatalytic resolution of (R,S)-styrene oxide using a novel epoxide hydrolase from red mung beans

Abstract

Chiral epoxides are commercially important starting materials for synthesis of active pharmaceutical ingredients and agrochemicals. A major challenge in synthetic chemistry is to produce such compounds in high yield with purity. There have been numerous current advances in the field of biotransformation particularly, hydrolytic kinetic resolution of epoxides using newly discovered enzymes (e.g. epoxide hydrolases). Epoxide hydrolase (EH) is a promising biocatalyst for the synthesis, as it enables racemic preparation of various epoxides and/or their corresponding diols in enantiopure form. In present study, partially purified epoxide hydrolase enzyme isolated from red mung beans was used for the first time for enantioselective hydrolysis of (R,S)-styrene oxide to (R)-1-phenyl-1,2-ethanediol. It was found that the optimal reaction temperature, buffer pH, and substrate concentration were 40°C, 7.5 and 20mM, respectively. Under optimized reaction conditions, conversion, Vmax and Km values were ∼44%, 8.2×10−3mol/L/min and 4.5mol/L, respectively.