Biocatalytic Asymmetric Reduction of Ketones

Significance

An efficient enantioselective, carbonyl reductase (Saccharomyces cerevisiae carbonyl reductase, SCR) catalyzed reduction of ketones is described. The gene encoding SCR has been identified, cloned, and expressed in E. coli cells. Two types of expression systems using NADPH as cofactor, which is regenerated by glucose dehydrogenase (GDH) to ensure a high turn-over, have been prepared. One is the tandem system, where the genes encoding SCR and GDH are located in the same plasmid, and in the other one, the two-plasmid system, each of the SCR and GDH genes is located in separated plasmids that coexist in a same E. coli cell. Using the recombinant E. coli cells a variety of useful optically active alcohols have been synthesized, and 11 out of 20 were enantiomerically pure (>98% ee).