Bioscience and Biotechnology Center, Nagoya University, Nagoya, Japan.
Adv Carbohydr Chem Biochem. 2019;76:1-64. doi: 10.1016/bs.accb.2018.09.003. Epub 2018 Nov 15.
Sialic acid (Sia) is involved in many biological activities and commonly occurs as a monosialyl residue at the nonreducing terminal end of glycoconjugates. The loss of activity of UDP-GlcNAc2-epimerase/ManNAc kinase, which is a key enzyme in Sia biosynthesis, is lethal to the embryo, which clearly indicates the importance of Sia in embryogenesis. Occasionally, oligo/polymeric Sia structures such as disialic acid (diSia), oligosialic acid (oligoSia), and polysialic acid (polySia) occur in glycoconjugates. In particular, polySia, a well-known epitope that commonly occurs in neuroinvasive bacteria and vertebrate brains, is one of the most well-known and biologically/neurologically important glycotopes in vertebrates. The biological effects of polySia, especially on neural cell-adhesion molecules, have been well studied, and in-depth knowledge regarding polySia has been accumulated. In addition, the importance of diSia and oligoSia epitopes has been reported. In this chapter, the recent advances in the study of diSia, oligoSia, and polySia residues in glycoproteins in neurology, and their history, definition, occurrence, analytical methods, biosynthesis, and biological functions evaluated by phenotypes of gene-targeted mice, biochemical features, and related diseases are described.
唾液酸（Sia）参与许多生物活性，通常作为糖缀合物非还原末端的单唾液酸残基存在。UDP-N-乙酰葡糖胺 2-差向异构酶/甘露糖胺激酶的活性丧失，这是 Sia 生物合成的关键酶，对胚胎是致命的，这清楚地表明了 Sia 在胚胎发生中的重要性。偶尔，糖缀合物中会出现寡聚/聚合 Sia 结构，如二唾液酸（diSia）、低聚唾液酸（oligoSia）和多聚唾液酸（polySia）。特别是多聚唾液酸，一种常见于神经侵袭性细菌和脊椎动物大脑中的已知表位，是脊椎动物中最著名和具有生物学/神经生物学重要性的糖基之一。多聚唾液酸的生物学效应，特别是对神经细胞黏附分子的影响，已经得到了很好的研究，并且积累了深入的知识。此外，二唾液酸和低聚唾液酸表位的重要性也有报道。在本章中，描述了神经科学中糖蛋白中二唾液酸、低聚唾液酸和多聚唾液酸残基的最新研究进展，以及它们的历史、定义、发生、分析方法、生物合成和通过基因靶向小鼠表型评估的生物学功能、生化特征和相关疾病。
