Chemoenzymatic enantioconvergent hydrolysis of p-nitrostyrene oxide into (R)-p-nitrophenyl glycol by a newly cloned epoxide hydrolase VrEH2 from Vigna radiata

• A newly cloned epoxide hydrolase VrEH2 was successfully overexpressed in E. coli.
• VrEH2 could enantioconvergently hydrolyze rac-pNSO affording (R)-pNPG.
• A chemoenzymatic enantioconvergent synthesis route was constructed.
• A chemoenzymatic synthesis of (R)-pNPG (99% ee) with 71.5% yield was achieved.

An epoxide hydrolase from Vigna radiata, VrEH2, was successfully cloned and overexpressed in Escherichia coli. Its temperature and pH optima were 30 °C and 6.5, respectively. VrEH2 showed an opposite regioselectivity towards (S)- and (R)-para-nitrostyrene oxide (pNSO), which enables it to catalyze the enantioconvergent hydrolysis of rac-pNSO affording (R)-p-nitrophenyl glycol (pNPG). Preparative synthesis of (R)-pNPG from rac-pNSO by a chemoenzymatic enantioconvergent hydrolysis route with one quarter time as using VrEH2 alone, gave (R)-pNPG in 99.0% ee and 71.5% overall yield after recrystallization, indicating the potential of VrEH2 as a promising biocatalyst for the preparation of enantiopure diols in organic synthesis.

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