碱性蛋白酶洗涤稳定性提高的研究进展

Research progress in improving the washing performance of alkaline protease

碱性蛋白酶是液体洗涤剂中使用量最大的一类酶制剂,应用于洗涤剂行业的碱性蛋白酶占碱性蛋白酶市场的60%以上。不同于粉状洗涤剂中的酶制剂被造粒所包裹,液体洗涤剂中的碱性蛋白酶直接暴露于溶液中,与洗涤剂成分如表面活性剂、洗涤助剂及漂白剂直接接触作用,使得蛋白酶洗涤稳定性下降。除此之外,蛋白酶在液体洗涤剂环境中存在普遍的自溶失活现象,对其洗涤性能造成不利影响。如何提升碱性蛋白酶的稳定性是液体洗涤剂领域中的一个热点问题。本文介绍了碱性蛋白酶的催化与失活机制,综述了几种常用于稳定碱性蛋白酶的策略,即添加稳定剂、分子改造和化学修饰,重点介绍了化学修饰中的聚乙二醇化修饰与多糖修饰,对比了两种修饰方法的过程与效果,并在最后对碱性蛋白酶稳定性提高策略进行了展望。

Alkaline protease is the most widely used enzyme in liquid detergents. The alkaline protease used in detergent industry accounts for more than 60% of the alkaline protease market. Different from the enzyme in powder detergents, which is wrapped due to granulation, the alkaline protease in liquid detergent is directly exposed to the solution and interacts with various deactivators such as surfactants, builders and bleaching agents. Anionic surfactants can cause significant changes in the conformation of alkaline protease, bleaching agents can partially oxidize the active center of protease, and chelators will compete with protease for Ca;to stabilize its active conformation, all resulting in the decline of washing stability of alkaline protease. In addition, the alkaline protease in liquid detergents suffers from the autolysis which can be enhanced by other deactivation factors, leading to an adverse effect on its washing performance. The stabilization of alkaline protease has been a hot topic. Researchers have made a lot of efforts on improving the stability of protease, which can improve the performance of enzyme preparation, reduce production costs and improve economic benefits. Extremozymes isolated from high or low temperatures, high salinity or alkaline environment have great potential in detergent industry, but it still needs a long time for industrial application because of the high cost of separation and cultivation. Herein, the catalytic and inactivation mechanisms of alkaline protease have been introduced, and the Ser-His-Asp catalytic triad is the key to the peptide bond hydrolysis activity of alkaline protease. Typical strategies for the stabilization of alkaline protease have been reviewed, including adding stabilizers, molecular modification and chemical modification. Adding stabilizers is the simplest but effective way to stabilize protease, and the stabilization effect of multi-component system is often better than that of a single stabilizer. Molecular modification is a new method of enzyme stabilization with high technical threshold, and the modification is not targeted at the enzyme itself, but involved in the process of enzyme translation, synthesis and expression. Chemical modification is a traditional strategy to improve the stability of enzyme, but seldom used for the enzymes for washing. Special attention has been paid to the introduction and comparison of polyethylene glycol modification and glycosylation modification. Finally, future perspectives of the stabilization stratagies for alkaline protease have been provided.