Rational design of the carbonyl reductase EbSDR8 for efficient biosynthesis of enantiopure (R)-3-chloro-1-phenyl-1-propanol

(R)-3-Chloro-1-phenyl-1-propanol ((R)-CPPO) is an important chiral intermediate for antidepressants. For its efficient biosynthesis, the carbonyl reductase EbSDR8 was engineered to asymmetrically reduce the unnatural substrate 3-chloro-1-phenyl-1-propanone (3-CPP) at high concentrations. Molecular docking and molecular dynamics simulations of the resulting mutants suggested enlarged substrate binding pocket and more reasonable interactions between the enzyme and the substrate or cofactor as the reasons for the enhanced catalytic activity and thus the remarkably improved conversion of high-concentration 3-CPP. Using the best mutant EbSDR8(G94A/L153I/Y188A/Y202M)as the whole-cell biocatalyst, reduction of 3-CPP (1.0 M) was conducted using 100% isopropanol as both the solvent and co-substrate for NADH regeneration, delivering (R)-CPPO with > 99%ee(p)and 95.5% conversion. This result suggests EbSDR8(G94A/L153I/Y188A/Y202M)as a potential biocatalyst for green production of (R)-CPPO at the industrial scale.