Construction of efficient enzyme systems for preparing chiral ethyl 3-hydroxy-3-phenylpropionate

Ethyl 3-hydroxy-3-phenylpropionate (EHPP), (R)-EHPP or (S)-EHPP, is an important chiral intermediate for pharmaceuticals. Its synthesis from ethyl benzoyl acetate (EBA) by alcohol dehydrogenase is regarded as a green method. However, scarcely any alcohol dehydrogenase has been reported competent in asymmetric synthesis of chiral EHPP at high EBA loading. Present study developed two robust and efficient bio-catalysts Mu-S2 and Mu -R4 for preparation of (S)-EHPP and (R)-EHPP respectively by rational design of alcohol dehydrogenase PcSDR from Pedobacter chitinilyticus based on molecular dynamics (MD) simulation analysis. BtGDH, a glucose dehy-drogenase from Bacillus toyonensis catalyzing the oxidation of glucose for cofactor regeneration, was co-expressed with the screened mutants to form enzyme systems Mu-S2-BtGDH and Mu-R4-BtGDH. After reaction condition optimization, Mu-S2-BtGDH and Mu-R4-BtGDH were efficient in the synthesis of (S)-EHPP (94% conv. and 99% e.e.) and (R)-EHPP (99% conv. and 98% e.e.) respectively in 100 mL scale under 500 mM of EBA loading in 10 h following a substrate continuous feeding mode. After purifying, the isolated yield for each EHPP enantiomer is > 93%. This work not only provides potential biocatalysts for the industrial production of (R)-EHPP and (S)-EHPP, but also enriches the constructure-function relationship of alcohol dehydrogenases.

Automated summary

The present study developed two robust and efficient bio-catalysts, Mu-S2 and Mu-R4, for the synthesis of (S)-EHPP and (R)-EHPP respectively. Through rational design of alcohol dehydrogenase PcSDR from Pedobacter chitinilyticus based on molecular dynamics simulation analysis, these catalysts exhibited high synthesis efficiency and selectivity under high EBA loading conditions. This work provides potential biocatalysts for the industrial production of (R)-EHPP and (S)-EHPP and enriches the constructure-function relationship of alcohol dehydrogenases.