结构修饰提高酶稳定性、活性

酶因其特异性和可持续性而成为广泛应用的绿色催化剂,其稳定性和催化活性是决定酶适用性的关键因素。为满足实际应用需求,通过蛋白质结构修饰赋予其所需的催化特性是当前的研究热点。提高热稳定性的策略有：引入非共价/共价相互作用（疏水相互作用、氢键、盐桥、芳香环相互作用、二硫键）、环截短、C端和N端工程,及增加脯氨酸/减少甘氨酸的数目等;获得具有高效性和多样性的生物催化剂的策略有：降低空间位阻、拓宽催化口袋、增加底物亲和力及调节活性位点灵活性等。然而,在稳定性或催化功能改造的过程中,新突变的引入会削弱其他功能,致使进化过程中稳定性和催化活性相互制约。因此,采用基于理性计算优选突变热点、基于多重蛋白质稳定性或活性改造策略的共进化,以及基于高度稳定的蛋白质骨架创造或/和优化蛋白质功能等多种策略克服酶稳定性-活性之间的权衡。本综述重点阐述了结构修饰方法在提高酶稳定性或/和催化活性方面的应用,并展望了该领域的未来发展前景。

Structural Modification to Enhance Enzyme Stability or/and Activity

The high specificity and sustainability of enzymes make them widely used as green catalysts, and their stability and catalytic activity are vital for their practical applicability. Recently, enzymes have been endowed with desired physical and catalytic properties via using protein structural modification. From the protein structural point of view, enzyme thermal stability has been improved by modulation of non-covalent/covalent interactions (hydrophobic interaction, hydrogen bonding, salt bridges, aromatic interaction and disulfide bonds), loop truncation, C-/N-terminal engineering, introduction of proline with highest conformational rigidity in the flexible region, and substitution of glycine with highest conformational entropy. Meanwhile, the catalytic function has been enhanced or altered by various methods, including reducing steric hindrance, widening the binding pocket, moderating substrate binding affinity and active site flexibility. While, the generation of new features or improvement of the existing features often comes at the expense of the other ones. Thus, strategies include screening suitable mutation sites, co-selection for stability and activity, and using highly stable proteins as the parental backbones are also discussed to overcome the stability-activity trade-off. This review summarized recent advances in structural modification to improve the stability or/and catalytic activity of enzymes and further provided a brief prospect in the future developments.