Efficient asymmetric synthesis of chiral alcohols using high 2-propanol tolerance alcohol dehydrogenase SmADH2 via an environmentally friendly TBCR system. Issue 1 (18th November 2019)

• Record Type: Journal Article
• Authors: Yang, Zeyu; Fu, Hengwei; Ye, Wenjie; Xie, Youyu; Liu, Qinghai; Wang, Hualei; Wei, Dongzhi
• Is Part Of: Catalysis science & technology. Volume 10:Issue 1(2020)
• Page Start: 70
• Page End: 78
• Publication Date: 2019-11-18
• Subjects: Catalysis -- Periodicals; 541.395
• DOI: 10.1039/c9cy01794a
• Languages: English
• ISSNs: 2044-4753

Abstract

Abstract : Based on substrate-coupled cofactor regeneration system, a high 2-propanol tolerance Sm ADH2 together with TBCR system can synthesise structurally diverse chiral alcohols at a high substrate loading with only 1.25 equivalents of 2-propanol. Abstract : Alcohol dehydrogenases (ADHs) together with the economical substrate-coupled cofactor regeneration system play a pivotal role in the asymmetric synthesis of chiral alcohols; however, severe challenges concerning the poor tolerance of enzymes to 2-propanol and the adverse effects of the by-product, acetone, limit its applications, causing this strategy to lapse. Herein, a novel ADH gene smadh 2 was identified from Stenotrophomonas maltophilia by traditional genome mining technology. The gene was cloned into Escherichia coli cells and then expressed to yield Sm ADH2. Sm ADH2 has a broad substrate spectrum and exhibits excellent tolerance and superb activity to 2-propanol even at 10.5 M (80%, v/v) concentration. Moreover, a new thermostatic bubble column reactor (TBCR) system is successfully designed to alleviate the inhibition of the by-product acetone by gas flow and continuously supplement 2-propanol. The organic waste can be simultaneously recovered for the purpose of green synthesis. In the sustainable system, structurally diverse chiral alcohols are synthesised at a high substrate loading (>150 g L −1 ) without adding external coenzymes. Among these, about 780 g L −1 (6 M) ethyl acetoacetate is completely converted into ethyl ( R )-3-hydroxybutyrate in only 2.5 h with 99.9% ee and 7488 g L −1 d −1 space–time yield. Molecular dynamics simulation results shed light on the high catalytic activity toward the substrate. Therefore, the high 2-propanol tolerance Sm ADH2 with the TBCR system proves to be a potent biocatalytic strategy for the synthesis of chiral alcohols on an industrial scale.