Purification and characterization of fluorinated ketone reductase from Geotrichum candidum NBRC 5767

• We successfully purified and characterized the fluorinated ketone reductase from Geotrichum candidum NBRC 5767.
• The fluorinated ketone reductase is highly selective for α fluorinated ketones.
• The fluorinated ketone reductase from G. candidum NBRC 5767 is unique and can be used in the synthesis of optically pure fluorinated alcohols.

Biocatalysts that can specifically catalyze the transformations of fluorinated compounds are rare. A novel NADPH-dependent fluorinated ketone reductase that reduces trifluoroacetophenone to (S)-trifluorophenylethanol with excellent enantioselectivity (ee > 99%) from Geotrichum candidum NBRC 5767 was isolated, purified, and characterized. Through ammonium sulfate fractionation and several chromatographies, this enzyme was purified to 95-fold with 3.5% yield. Gel filtration chromatography with SDS-PAGE revealed this protein to be a dimer of 60 kDa subunits. An investigation of the substrate specificity of the purified enzyme revealed that it was highly selective for ketones containing fluorines at the α position.