Introduction to Sialic Acid Structure, Occurrence, Biosynthesis and Function

Sialic acids (Sia) are a family of 9-carbon α-keto acid aminosugars found predominantly at the non-reducing end of oligosaccharide chains on glycoproteins and glycolipids. Since their discovery in the late 1930s, and subsequent naming by Blix, Gottschalk and Klenk (Nature. 1957; 179: 1088), Sia are now recognized as occurring ubiquitously in nature (except plants), and being involved in numerous biologically important processes. In particular, the growing awareness of the significance of Sia in human health and disease has led to an increase in research into Sia chemistry, biochemistry and cell biology. In this chapter, the structure and occurrence of Sia will be summarized, as well as aspects of Sia chemistry, biochemistry and cell biology not covered in subsequent chapters of this eBook are also presented. Throughout this, and subsequent chapters of this eBook the abbreviations and nomenclature summarised in Schauer and Varki, (In Essentials of Glycobiology 2^nd Ed, Cold Spring Harbor (NY): Cold Spring Harbor Laboratory Press; 2009) will be used. Importantly, wherever appropriate the reader will be directed to the relevant chapters of this eBook, or extensive reviews for further detail.

Keywords: Sialic acid, sialobiology, sialylation, O-acetylation, sialic acid structure, sialic acid occurrence, sialic acid biosynthesis, sialic acid function.