BioVT-2010-05 [BibTeX]
Kazuhito Nagayama, Antje Spieß, Jochen Büchs:
Immobilization conditions of ketoreductase on enantioselective reduction in a gas-solid bioreactor
Biotechnology Journal, 2010, 5(5), 520-525
Abstract:
The immobilization conditions of commercial ketoreductase for continuous enantioselective reduction
in the gas-phase reaction were investigated with respect to the immobilization efficiency
(residual activity and protein loading) and the gas-phase reaction efficiency (initial reaction rate,
half-life, and enantioselectivity). For the analyses, ketoreductase was first immobilized by physical
deposition on glass supports and the reduction of 2-butanone to (S)-2-butanol with the concomitant
regeneration of NADH by 2-propanol was used as a model reaction. The optimal conditions
of enzyme immobilization were obtained using an absolute pressure of 100 hPa for drying, a pH
between 6.5 and 7.0, and a buffer concentration of 50 mM. The buffer concentration in particular
had a strong effect on both the enzyme activity and enantioselectivity. Under optimal immobilization
conditions, the thermostability of ketoreductase in the gas-phase system was enhanced compared
to the aqueous-phase system, while the enantioselectivity was successfully maintained at a
level identical to that of the native enzyme. These results indicate that the gas-phase reaction has
a great potential for industrial production of chiral compounds, but requires careful optimization
of immobilization conditions for the reaction to progress effectively.
Keywords:
biocatalysis, enantioselectivity, gas phase, ketoreductase, reduction