酶的改造及其催化工程应用

The Improvement of Enzyme Properties and Its Catalytic Engineering Strategy

酶作为生物催化剂在食品、饲料、化妆品以及医药等诸多领域逐渐发挥重要作用。但是,酶对外界环境如p H和温度等很敏感,而实际的反应条件和生物体的生理环境差异较大,因此酶在实际应用中不稳定、容易失活,催化效率下降。酶的这一特点大大限制了其工业化应用。目前,定向进化、糖基化以及化学修饰等方法被广泛用于酶分子的改造以提高其稳定性、催化效率以及扩大其底物范围。其中,定向进化通过模拟自然进化机制,在体外改造基因从而获得性能优化的酶突变体,已经成为了酶改造的重要技术。在酶的实际应用过程中,介质工程、固定化以及多酶催化体系构建等技术被广泛用于提高酶的催化效率。其中,多酶催化体系由于其底物通道效应可以显著提高级联酶反应的效率而备受关注。本文首先重点介绍了近年酶应用的现状,然后从酶定向进化、糖基化以及化学修饰的角度总结了酶改造的方法,最后从介质工程、酶固定化以及体外多酶催化体系等方面进一步总结了酶实际应用中的催化工程策略。

Enzymes play an increasingly important role in many industrial fields such as food, feed, cosmetics and pharmacy. However, enzymes are susceptible to the external environment such as pH and temperature, and the practical operational conditions for enzymes are dramatically different from their physiological conditions, so most enzymes are not sufficiently stable and they are prone to lose their activity under practical operation. This has largely limited their wider industrial application. Currently, directed evolution, glycosylation and chemical modification have been extensively used to improve the enzyme stability, activity and expand the substrate scope. Among them, directed evolution, through which mutants bearing desired properties are obtained by gene diversification manipulation and library screening in vitro, has become a popular technique for enzyme modification. In practical application, medium engineering, immobilization and multi-enzyme complexes have been widely adopted to enhance the catalytic efficiency of enzyme. Among them, multi-enzyme complexes have gained special attention recently due to its substrate channeling effect which can significantly increase the reaction rate for cascade enzymatic reactions. The recent progress of enzyme application is introduced. Then, the popular techniques including directed evolution, glycosylation and chemical modification for the improvement of enzyme properties are reviewed. At last, the techniques including medium engineering, immobilization and multi-enzyme complex for the catalytic engineering of enzyme in practical application are summarized.