Toward Designing a Novel Oligopeptide-Based Deep Eutectic Solvent: Applied in Biocatalytic Reduction

Abstract

We report a new method for developing a deep eutectic solvent (DES) and its application as a cosolvent in biocatalytic reactions. A novel oligopeptide-based DES containing choline chloride (ChCl) and glutathione (GSH, comprised of Glu, Cys, and Gly) was designed and synthesized. Using this oligopeptide-based DES as a cosolvent, we achieved efficient asymmetric reduction of 3,5-bis(trifluoromethyl) acetophenone catalyzed by Trichoderma asperellum ZJPH0810. Under optimized conditions, the substrate loading increased 2-fold in the ChCl/GSH-containing system compared with that in aqueous buffer (100 vs 50 mM), with a yield >90% and enantiomeric excess value >99%. To broaden the application of the established ChCl/GSH-containing system in biocatalysis, the asymmetric reductions of different substrates in developed reaction medium were further investigated. Compared with the aqueous system, the ChCl/GSH-containing system enhanced substrate loading (50 vs 100 mM when catalyzed by Candida tropicalis 104), obviously improved the yield (i.e., from 70.4 to 87.6% when catalyzed by C. tropicalis 104, from 65.9 to 83.8% by Candida parapsilosis ZJPH1305), and shortened the reaction time greatly (30 vs 24 h when catalyzed by C. tropicalis 104, or 1.5 vs 1.0 h by recombinant Escherichia coli). These findings provide valuable insight for the design of task-specific and sustainable oligopeptide-based DESs for biocatalysis.