| The recent progresses and key problems in the biocatalysis in organic media, such as media engineering, catalyst engineering, are reviewed. Studies over the past 15 years have revealed that not only the change of solvent is feasible, but also in such seemingly hostile environments enzyme will become more stable and can catalysis reactions impossible in water. Of particular importance has been the discovery that enzymatic selectivity, including substrate, stereo-, regio- and chemo-selectivity, can be markedly affected, and some times even inverted by the solvent. It have been hound that enzyme-catalyzed reactions in organic solvents have numerous potential applications such as in the chiral drug and intermediate of fine chemicals, some of which are already commercialized.The synthesis of n-butyl acetate by transesterification of vinyl acetate and n-butanol catalyzed by lipase in hexane was studied. A simple procedure was introduced which can control a certain water activity by using different salt/salt hydrate pairs. The principle of the method was analyzed according to the phase rule. The effect of water activity on the enzymatic reaction in organic solvent was investigated then.Lipases from six different sources were immobilized on Celite and five types of salt. Compared to the free enzyme, the transesterification activities in hexane for lipases immobilized on EDTA-Na2 increased by 463%, 2700% and 1215% for the lipase from Candida rugosa (CRL), Candida sp. (CSL) and Pseudomonas sp. (PSL) respectively. With the addition of 0.5% sucrose for CRL and 1.0% sorbitol for PSL as the lyoprotectant during lyophilization process, transesterification activity increased by 100% and 13% respectively, compared to the immobilized enzyme on EDTA-Na2 without lyoprotectant.35 lipases were screened for the irreversible transesterification of 1-phenyl alcohol in free-solvent system. Some of them had higher reaction activity and enantioselectivity. Finally lipase 22 was chosen as the best enzyme to be optimized with the reaction conditions. The catalytic behaviors of lipase 22 were investigated. It was found that under the optimal conditions, with the temperature of 40℃ and rotation speed of 150 rpm, 20 mg enzyme was enough for 600mmol/L phenyl ethanol in 2 ml reaction volume. At the optimized reaction conditions, the conversion rate of R-α-phenyl ethanol reached 98.9%, in the meanwhile the e.e. value of S-phenyl ethanol and R-a- phenyl ethyl acetate were 97.8% and 99.4% respectively at the end of reaction.The reaction process of reused enzyme was studied. It was found that at the reaction time of 550min, the conversion rate of R-a-phenyl ethanol was 97.3% 72.5%and 65.7% respectively when enzyme was used for the first, second and third times. The e.e. value of S-1-phenyl ethanol dropped about 46%, but the e.e. of R-1-phenylethyl acetate remained almost the same.Chiral intermediates of CPBAc and CPBA were separated by HPLC. The optimized conditions of chromatography were as follows: chiral column was Sumichiral OA-4400 (25cmx4.6mm, 5μm), mobile phase was n-hexane/l,2-DicWoroethane/ethanol (87:10:3, volume ratio), flow rate 1.0 ml min-1, UV detection wavelength 254nm, column temperature 15℃, sample injection volume 5μl. Under these conditions, experimental results showed good linear relationship between peak area and concentration of CPBAc and CPBA at the range of test concentrations.33 Upases from different sources were screened for the reversible alcoholysis of CPBAc. 10 of them showed higher catalytic activity and were screened again. Lipase 22, 24, and 33 showed higher enantioselectivity. 15 different organic solvents including mixed solvents and 14 different alcohols were compared. THF and dichloromethane were the best organic media and methanol was the best acyl accepter. Thus the preferable system for the asymmetric reaction was lipase 22, THF and methanol.When the reaction was carried out in the preferable systems above, several factors mat affected the reaction were investigated in detail, su...
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