title: Effect of additives on gas-phase catalysis with immobilised Thermoanaerobacter species alcohol dehydrogenase (ADH T).
abstract: This paper presents a strategy for preparing an efficient immobilised alcohol dehydrogenase preparation for a gas-phase reaction. The effects of additives such as buffers and sucrose on the immobilisation efficiency (residual activity and protein loading) and on the gas-phase reaction efficiency (initial reaction rate and half-life) of Thermoanaerobacter sp. alcohol dehydrogenase were studied. The reduction of acetophenone to 1-phenylethanol under in situ cofactor regeneration using isopropanol as co-substrate was used as a model reaction at fixed reaction conditions (temperature and thermodynamic activities). A strongly enhanced thermostability of the enzyme in the gas-phase reaction was achieved when the enzyme was immobilised with 50 mM phosphate buffer (pH 7) containing sucrose five times the protein amount (on weight/weight basis). This resulted in a remarkable productivity of 200 g L(-1) day(-1) even at non-optimised reaction conditions. The interaction of additives with the enzyme and water affects the immobilisation and gas-phase efficiencies of the enzyme. However, it was not possible to predict the effect of additives on the gas-phase reaction efficiency even after knowing their effect on the immobilisation efficiency.
authors.affiliation: Biochemical Engineering, Sammelbau Biologie, RWTH Aachen University, Worringerweg 1, 52056, Aachen, Germany.
authors.forename: A H
authors.initials: AH
authors.lastname: Trivedi
authors.forename: A C
authors.initials: AC
authors.lastname: Spiess
authors.forename: T
authors.initials: T
authors.lastname: Daussmann
authors.forename: J
authors.initials: J
authors.lastname: Büchs
mesh_terms: D000098:Acetophenones / Q000378:metabolism; D000327:Adsorption; D000426:Alcohol Dehydrogenase / Q000737:chemistry / Q000378:metabolism*; D001592:Benzyl Alcohols / Q000378:metabolism; D019149:Bioreactors; D001709:Biotechnology / Q000379:methods*; D002384:Catalysis; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008863:Microspheres; D013395:Sucrose / Q000378:metabolism; D046968:Thermoanaerobacter / Q000201:enzymology*
chemical_list: D000098:Acetophenones; D001592:Benzyl Alcohols; D004800:Enzymes, Immobilized; D013395:Sucrose; C002017:methylphenyl carbinol; D000426:Alcohol Dehydrogenase; C038699:acetophenone