Manipulating Activity and Chemoselectivity of a Benzaldehyde Lyase for Efficient Synthesis of α-Hydroxymethyl Ketones and One-Pot Enantio-Complementary Conversion to 1,2-Diols

Abstract

The α-hydroxymethyl ketone motif has been widely found in many pharmaceutically important molecules and used as a key intermediate in the synthesis of various fine chemicals and natural products. Hydroxymethylation of aldehydes with formaldehyde catalyzed by thiamine diphosphate (ThDP)-dependent enzymes is considered a highly valuable approach in terms of atom economics and sustainability, while low activity and chemoselectivity restricted its widespread application. In this study, a benzaldehyde lyase (BAL) with high activity and catalytic efficiency was acquired by enzyme screening and engineering, which catalyzed the hydroxymethylation of furfural at the concentration of 700 mM. Crystal structural analysis and molecular dynamics studies revealed that the activity and chemoselectivity of BAL were improved by reshaping the conformation of the substrate entrance tunnel. Furthermore, a one-pot concurrent enzymatic process involving BAL-catalyzed hydroxymethylation of aldehydes and subsequent asymmetric reduction with carbonyl reductase was developed, offering a highly efficient way to produce chiral 1,2-diols from simple aldehydes, with high ee values (97–99%) in good yields (52–97%). The significantly improved activity and chemoselectivity demonstrated the potential of the engineered BAL in the industrial production of α-hydroxymethyl ketones, which could readily enable the synthesis of other high-value-added chemicals from simple aldehydes and formaldehyde.