唾液酸苷酶的催化机理及水解与合成寡糖进展

唾液酸苷酶(EC.3.2.1.18)是一类重要的糖苷水解酶,在动物和微生物中广泛存在.该类酶催化寡糖或糖缀合物上非还原末端唾液酸水解,具有重要的生物学功能,如参与溶酶体降解代谢物、癌症发生、微生物致病等多种生理和病理过程.除了水解活性外,有的唾液酸苷酶还具有转糖基活性,能够以唾液酸单糖或糖苷为糖基供体,催化唾液酸转移到受体分子上,一步合成寡糖和糖苷化合物.这种合成活性对于唾液酸相关糖链的大量获得具有重要意义,有利于推动该类寡糖的基础研究及其在食品和医药中的应用.本文综述了唾液酸苷酶的结构和催化机理、生理功能、转糖基作用及其在寡糖合成中的应用.

Progress in Catalytic Mechanism of Sialidases and Their Functions in Oligosaccharide Hydrolysis and Synthesis

Sialidases (EC.3.2.1.18) are an important class of glycosidases that are widely found in animals and microorganisms. These enzymes catalyze the cleavage of the terminal sialic acid from various oligosaccharides and sialoglycoconjugates, and play important roles in diverse biological processes such as lysosomal catabolism, tumorigenesis and microbial pathogenesis. Generally, sialidases cleave glycosidic linkages. Under appropriate reaction conditions in vitro, however, the enzymes can catalyze the formation of the glycosidic linkages by transglycosylation reaction. This synthesis activity is important for the large acquisition of sialosides, which would be helpful to promote the basic research on their functions as well as their applications in food and pharmaceutical industries. This paper reviews the structure and catalytic mechanism of sialidases, physiological function, transglycosylation and their application in oligosaccharide synthesis.