Identification of ketone reductase ChKRED20 from the genome of Chryseobacterium sp. CA49 for highly efficient anti-Prelog reduction of 3,5-bis(trifluoromethyl)acetophenone

A strain of Chryseobacterium sp. CA49 was isolated to perform efficient anti-Prelog reduction of 3,5-bis(trifluoromethyl)acetophenone (1a) to enantiopure (R)-3,5-bis(trifluoromethyl)-1-phenylethanol ((R)-1b), a key intermediate for the chiral drug Aprepitant. The draft genome sequencing of the strain revealed 27 putative short chain dehydrogenases/reductases of COG1028. Their activity and stereoselectivity were assayed after expression in Escherichia coli as recombinant proteins, and the key enzyme ChKRED20 was identified with excellent activity and stereoselectivity. The lyophilized powder of the crude recombinant enzyme was applied to generate (R)-1b with >99% conversion and >99.9% enantiomeric excess at a substrate concentration of 150 g/l within 24 h by using 2-propanol as the co-substrate. The results indicate great potential for industrial-scale application of ChKRED20.