Stereoselective synthesis of chiral δ-lactones via an engineered carbonyl reductase

A carbonyl reductase variant, SmCRM5, from Serratia marcescens was obtained through structure-guided directed evolution. The variant showed improved specific activity (U mg(-1)) towards most of the 16 tested substrates and gave high stereoselectivities of up to 99% in the asymmetric synthesis of 13 gamma-/delta-lactones. In particular, SmCRM5 showed a 13.8-fold higher specific activity towards the model substrate, i.e., 5-oxodecanoic acid, and gave (R)-delta-decalactone in 99% ee with a space-time yield (STY) of 301 g L-1 d(-1). The preparative synthesis of six delta-lactones in high yields and with high enantiopurities showed the feasibility of the biocatalytic synthesis of these high-value-added chemicals, providing a cost-effective and green alternative to noble-metal catalysis.

Automated summary

A carbonyl reductase variant, SmCRM5, obtained from Serratia marcescens through structure-guided directed evolution, showed improved specific activity towards multiple substrates and high stereoselectivities in the asymmetric synthesis of gamma-/delta-lactones.