Enantioselective Hydrolysis of Racemic and Meso-Epoxides with Recombinant Escherichia coli Expressing Epoxide Hydrolase from Sphingomonas sp. HXN-200: Preparation of Epoxides and Vicinal Diols in High ee and High Concentration

Abstract

A unique epoxide hydrolase (SpEH) from Sphingomonas sp. HXN-200 was identified and cloned based on genome sequencing and expressed in Escherichia coli. The engineered E. coli (SpEH) showed the same selectivity and substrate specificity as the wild type strain and 172 times higher activity than Sphingomonas sp. HXN-200 for the hydrolysis of styrene oxide 1. Hydrolysis of racemic styrene oxide 1, substituted styrene oxides 3, 5–7, and N-phenoxycarbonyl-3,4-epoxypiperidine 8 (200–100 mM) with resting cells of E. coli (SpEH) gave (S)-epoxides 1, 3, 5–7 and (−)-8 in 98.0–99.5% enantiomeric excess (ee) and 37.6–46.5% yield. Hydrolysis of cyclopentene oxide 9, cyclohexene oxide 10, and N-benzyloxycarbonyl-3,4-epoxypyrrolidine 11 (100 mM) afforded the corresponding (R, R)-vicinal trans-diols 12–14 in 86–93% ee and 90–99% yield. The ee of (1R, 2R)-cyclohexane-1,2-diol 13 was improved to 99% by simple crystallization. These biotransformations showed high specific activity (0.28–4.3 U/mg cdw), product concentration,...