Biotechnology Bulletin ›› 2020, Vol. 36 ›› Issue (1): 73-80.doi: 10.13560/j.cnki.biotech.bull.1985.2019-0624

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Enantioconvergent Hydrolysis of m-Nitrostyrene Oxide by Phaseolus vulgaris Epoxide Hydrolase

LI Chuang1, WEN Zheng1, LIU Chang2, WU Min-chen2   

  1. 1. School of Biotechnology,Jiangnan University,Wuxi 214122;
    2. Wuxi School of Medicine,Jiangnan University,Wuxi 214122
  • Received:2019-07-11 Online:2020-01-26 Published:2020-01-08

Abstract: This work aims to provide a superior biocatalyst for producing optically pure(R)-m-nitrophenyl-1,2-ethanediol(mNPED)via studying the catalytic properties of PvEH2,a Phaseolus vulgaris epoxide hydrolase,in the enantioconvergent hydrolysis of racemic(rac-)m-nitrostyrene oxide(mNSO). The engineered Escherichia coli strain expressing the recombinant PvEH2,designated E. coli/pveh2,was constructed. Using rac-mNSO as substrate,the EH activity and regioselectivity of E. coli/pveh2 were assayed by chiral chromatography. Then,according to the effects of several organic solvents and their dosages on enzymatic activity,the buffer/co-solvent reaction system was screened and optimized. Results showed that the transcription level of PvEH2 gene in P. vulgaris might be affected by the induction factors in vitro. The EH activity of E. coli/pveh2 was 15.4 U/g dry cell,and its regioselectivity coefficients,αS and βR,were 90.3% and 96.4%,respectively. In the optimized phosphate buffer containing 5%(V/V)glycerol,the maximum allowable substrate concentration(40 mmol/L)was 4 times higher than that in sole buffer.(R)-mNPED with 84.9% eep and 90.2% yield was obtained at 12 h reaction. E. coli/pveh2 or PvEH2 demonstrates an excellent regioselectivity in the hydrolysis of rac-mNSO,thus making it a promising biocatalyst to prepare optically pure(R)-mNPED.

Key words: epoxide hydrolase, enantioconvergent hydrolysis, m-nitrostyrene oxide, m-nitrophenyl-1, 2-ethanediol