脱脂棉固定化脂肪酶的非水活性与稳定性

Nonaqueous Activity and Stability of Pseudomonas cepacia Lipase Immobilized on Absorbent Cotton Fiber

脂肪酶具有非水催化作用,但其非水催化活性和稳定性需进一步提高,这是非水酶学的瓶颈问题之一。理想的策略是模拟脂肪酶的界面活化机制,以大分子代替水,优化、稳定化和有效分散酶蛋白,阻止其在有机相中变性。因此,选用多羟基、比表面积大、惰性、且与酶蛋白能兼容的大分子——脱脂棉纤维,作为固定化载体,以1∶0.9的质量比,通过物理吸附,将假单胞菌脂肪酶(Pseudomonas cepacia lipase)固定在脱脂棉纤维上。在催化己醇与乙酸乙烯酯的转酯反应中,反应1 h,脱脂棉固定化脂肪酶转化底物的能力是酶粉的3.7倍。在每次6 h共6次的循环催化中,固定化酶和酶粉转化底物的能力分别平均每次降低约0.3%和2.4%。表明脱脂棉固定化脂肪酶的非水活性,尤其是稳定性明显提高。这为通过固定化有效提高脂肪酶的非水催化作用,以满足工业应用的需要,提供了一种有效的途径和重要参考。

Catalysis of lipases exists in nonaqueous media, but their catalysis with low activity and stability needs further improvement. That is one of bottleneck problems in nonaqueous enzymology. The desired strategy was that simulation on the interracial activation of lipases, namely replacing water with maeromolecule, to optimize, stabilize and disperse enzyme proteins so as to hold back denature in organic phases. Then the macromolecules should have numerous hydroxyl groups, large specific surface, inert and compatibility with enzyme proteins. Absorbent cotton fiber happened to own these characteristics and was employed as immobilization carrier to prepare immobilized Pseudomonas cepacia lipase in a mass ratio of 1：0.9 （lipase： cotlon） by physical adsorption. In catalyzing transesterification between hexanol and vinyl acetate, the prepared cotton-lipase was 3.7 folds of native lipase in transformation ability of hexanol after 1 hour. In a catalytic cycle of 6 times and 6 hours once, the ability of immobilized and native lipases transforming substrate averagely was reduced by about 0.3% and 2.4% , respectively. It showed that cotton-lipase had obvious increase in the nonaqueous activity, especially the stability. This study presented a way for effective enhancement of nonaqueous catalysis of lipases by immobilization method so as to meet the requirements on their applications in industry.