Objective: To identify an esterase-mediated kinetic resolution of secondary alcohols in non-aqueous medium.
Results: An esterase, EST4, from a marine mud metagenomic library, showed high activity and enantioselectivity for the kinetic resolution of secondary alcohols in non-aqueous medium. Using 1-phenylethanol as the model alcohol, the effects of organic solvents, acyl donors, molar ratio, temperatures and biocatalyst loading on the kinetic resolution catalyzed by the EST4 whole-cell biocatalyst were investigated and optimized. The optimized methodology was effective on resolving 16 various racemic secondary alcohols in neat n-hexane, providing excellent enantiomeric excess (up to 99.9 % ee). Moreover, EST4 exhibited a strong tolerance for high substrate concentration (up to 1 M), and the optical purity of the desired secondary alcohols was kept above 99 % ee.
Conclusion: The esterase EST4 is a promising biocatalyst for the enantioselective synthesis of various alcohols and esters with interesting practical applications.
Keywords: Enantioselectivity; Esterase; High substrate concentration tolerance; Kinetic resolution; Secondary alcohols; Transesterification.