Novel enzyme materials-utilizing in organic media

在过去的十年中，酶在有机介质中的应用引起了人们的广泛关注，因为它具有一些与在水中相比显着的新特性。生物催化剂工程已成功地用于改善有机介质中的生物催化，获得稳定的生物催化剂是生物技术的主要目标。酶在非水溶剂中可以催化疏水化合物的合成反应，如酯化、类固醇转化和肽的形成。与传统的化学合成相比，酶转化的底物特异性和反应性非常高。因此，酶促反应的应用有望产生具有工业规模的光学活性材料。然而，为了充分利用有机介质中的生物催化作用，从降低底物扩散限制和提高反应速率的角度出发，有必要对酶进行修饰，使其可溶于有机溶剂。此外，虽然在悬浮状态下使用粉末状酶很简单，但由于其非均质性，反应速率通常很低，并且需要几天才能达到较高的反应收率。本研究开发了一种利用油包水乳液制备表面活性剂-酶配合物的新方法。研究了表面活性剂-脂肪酶配合物的制备条件。采用表面活性剂-脂肪酶配合物，在有机溶剂中对苯甲醇与月桂酸进行了酯化反应。脂肪酶在疏水有机溶剂中的酶活性通过表面活性剂包埋而显著增强。表面活性剂-脂肪酶配合物在有机介质中催化酯化反应。表面活性剂-脂肪酶复合物的酯化速率远高于粉状脂肪酶。脂肪酶复合物的活性在很大程度上取决于包覆的表面活性剂和制备过程中的水pH值。与天然脂肪酶相比，表面活性剂-脂肪酶配合物在高温下具有热稳定性。此外，脂肪酶复合物具有较高的储存稳定性。这种修饰方法将使我们能够利用许多在有机介质中未表现出酶活性的酶作为新的生物催化剂。少

The utility of enxymes in organic media has attracted much interest during the last ten years due to some remarkable novel properties compared to those in water. Biocatalyst engineering has been used successfully to improve biocatalysis in organic media and obtaining stable biocatalysts is a main target of biotechnology. Enzymes in nonaqueous solvents can catalyze a synthesis reaction of hydrophobic compounds such as esterification, steroid conversions and peptide formation. The substrate specificity and reactivity in an enzyme conversion are extremely high compared with those of conventional chemical synthesis. Thus an application of enzymatic reaction has been expected to produce optically active materials with an industrial scale.However, in order to take full advantage of the biocatalysis in organic media, it is necessary to modify the enzyme to be soluble in an organic solvent from the viewpoint of reduced diffusional limitations of substrates and increase in the reaction rate. Al … More though using a powder enzyme in a suspension state is simple, the reaction rate is usually very low due to the heterogeneity and several days are required to attain a high reaction yield. In this study, a novel preparation method for surfactant-enzyme complexes has been developed utilizing water-in-oil emulsions. Preparation conditions to obtain a suitable surfactant-lipase complex were investigated. Using the surfactant-lipase complexes, the estarification of benzyl alcohol with lauric acid was conducted in organic solvents. The enzymatic activity of lipase in a hydrophobic organic solvent was significantly enhanced by entrapping in a surfactant matrix. The surfactant-lipase complex catalyzed the esterification effect ively in organic media. The esterification rate from the surfactant-lipase complex was much higher than that from the powder lipase. The activity of the lipase complex strongly depends on the entrapping surfactant and the aqueous pH in the preparation. The surfactant-lipase complexes were thermostable at high temperature compared to the native lipase. Furthermore, the lipase complex showed a high storage stability. This modification method will enable us to utilize a lot of enzymes as new biocatalysts which had not shown enzymatic activity in organic media. Less