De novo construction of multi-enzyme system for one-pot deracemization of (R,S)-1-phenyl-1,2-ethanediol by stereoinversion of (S)-enantiomer to the corresponding counterpart

• Key enzymes for redox-based deracemization were selected by systematic evaluation.
• Multi-enzyme system was artificially constructed for one-pot deracemization.
• Enzyme-coupled deracemization system involved cofactor self-recycling.
• Optically active product was achieved by biocatalytic system and process regulation.

Deracemization via oxidoreductive stereoinversion is one of the most attractive methods for the preparation of enantiomerically pure compounds. However, available enzymatic system is yet limited for efficiently catalyzing deracemization to produce optically pure alcohol in certain configuration. Through evaluation of available stereoselective oxidoreductases on activity, selectivity, and cofactor dependency, the suitable candidates were obtained to construct the enzymatic deracemization system involving cofactor self-recycling. For deracemizing (R,S)-1-phenyl-1,2-ethanediol (PED) to (R)-PED, a facile one-pot system was established by combination of two stereoselective oxidoreductases, the stereospecific carbonyl reductase 1 (SCR1) and the ketoreductase (KRD). To rebalance the activities and catalytic functions of different enzymes involved in the multi-enzyme system, the reaction conditions of SCR1-catalyzed oxidation and KRD-mediated reduction were optimized, respectively. Consequently, the deracemization system involving cofactor self-recycling was built to produce (R)-PED with the optical purity of 95.50%e.e. and the yield of 91.62% from the corresponding racemate (1 g L−1), under the optimal reaction conditions including activity ratio of SCR1/KRD 1:4 (SCR1 10 U mL−1 and KRD 40 U mL−1), molar ratio of NADP+/NADPH 3:1, 30 °C, and pH 7.0. Therefore, the developed strategy would be useful to construct the multi-enzyme deracemization system based on systematic evaluation of enzyme features.

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