Study on Mesophilic and Thermophilic Alcohol Dehydrogenases in Gas-Phase Reaction

摘要

The initial reaction rate and the thermostability of the mesophilic alcohol dehydrogenase (ADH) from Lactobacillus brevis (LBADH),and the thermophilic ADH from Thermoanaerobacter sp.(ADH T) in gas-phase reaction were compared.The effects of water activity,cofactor-to-protein molar ratio,and reaction temperature on the reduction of acetophenone to 1-phenylethanol were studied.An optimal water activity of 0.55 in terms of productivity was found for both ADHs.The cofactor-to-protein molar ratio was chosen slightly higher than equimolar to increase both activity and thermostability.An excellent optimal productivity of 1000 g centre dot L~(-1) centre dot d~(-1) for LBADH and 600 g centre dot L~(-1) centre dot d~(-1) for ADH T was found at 60 deg C,while the highest total turnover numbers with respect to the enzyme were achieved at 30 deg C and amounted to 4.2 million for LBADH and 1.7 million for ADH T,respectively.Interestingly,the ADH from the mesophilic L.brevis showed the higher thermostability in the nonconventional medium gas phase.