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

A carbonyl reductase variant, Sm CR M5 , 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 γ-/δ-lactones.