摘要
以丁酸与丁醇的酯化为模型反应，研究了假单胞菌脂肪酶的非水相催化性质。有机相中酶的催化作用需要一定的水分，最适水含量因溶剂的不同而有所差异。通常，极性强的溶剂其最适水含量高；当以水活度衡量时，各溶剂间的差别消失，最适水活度均在０．５～０．６之间。有机溶剂中酶的热稳定性较水溶液中明显提高，在环己烷中８０℃保温６ｈ酶活力仍保留约８０％；连续使用５次，酶活损失不到１０％．在环己烷中酶的最适作用温度为５０℃，比水溶液中略高；最适作用ｐＨ为９．０，与水溶液中相近。
The catalytic properties in nonaqueous media of a lipasefrom Pseudomonas sp. were studied by using the esterification of butyric acid with butanol as the model reaction. A small amount of water was found to be necessary for the lipase activity in organic solvents; but the optimum water contents varied considerably among the different solvents, with more hydrophilic solvents usually have higher optimum water contents. When water activity was employed to quantify water, the differences among the solvents disappeared, an optimum water activity of 0.5～0.6 existed for all the solvents used. The thermal stability of the lipase in organic solvents was significantly higher than that in aqueous solution, it remained almost 80% of the original activity after incubation at 80℃ in cyclohexane for 6h; its activity loss was less than 10% after being successively used for 5 runs. The optimum temperature of the lipase in cyclohexane was 50℃, which is slightly higher than that in aqueous solution; the optimum pH was 9.0, nearly the same with that in aqueous solution.
关键词
脂肪酶
假单胞菌
非水相
催化性质
lipase
Pseudomonas sp.
nonaqueous medium
catalytic
