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Immobilization conditions of ketoreductase on enantioselective reduction in a gas‐solid bioreactor
Author(s) -
Nagayama Kazuhito,
Spiess Antje C.,
Büchs Jochen
Publication year - 2010
Publication title -
biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.144
H-Index - 84
eISSN - 1860-7314
pISSN - 1860-6768
DOI - 10.1002/biot.200900287
Subject(s) - enantioselective synthesis , thermostability , chemistry , bioreactor , biocatalysis , immobilized enzyme , butanol , chromatography , aqueous two phase system , phase (matter) , catalysis , organic chemistry , chemical engineering , enzyme , reaction mechanism , ethanol , engineering
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.