Efficient NADPH recycling in enantioselective bioreduction of a ketone with permeabilized cells of a microorganism containing a ketoreductase and a glucose 6-phosphate dehydrogenase

Abstract

We have demonstrated, for the first time, the efficient recycling of NADPH in a bioreduction with permeabilized cells of a single microorganism. Permeabilized cells of Bacillus pumilus Phe-C3 containing an NADPH-dependent ketoreductase and a glucose 6-phosphate dehydrogenase (G-6-PDH) were successfully used for the reduction of ethyl 3-oxo-4,4,4-trifluorobutanoate (1) to give (R)-ethyl 3-hydroxy-4,4,4-trifluorobutanoate (2) in 95% ee with the recycling of NADPH for 4220 times from the externally added NADP+. The permeabilized cells were shown to be stable and active for a long period, allowing for high product concentration with high cofactor TTN by continuing the bioreduction with renewed addition of NADP+. This provides with not only a practical synthesis of (R)-2 but also a useful method applicable to many microbial oxidoreductions, since G-6-PDH is a very common enzyme existing in many microorganisms. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.