Chemistry of the Glycosidic Bond

Abstract

Because of the importance and the role the carbohydrates play in living organisms, the formation and hydrolysis of glycosidic bond are probably the two most important reactions in carbohydrate chemistry. Just as the amino acids are the building blocks for the synthesis of peptides and proteins in living organisms, the monosaccharides are the building blocks for the synthesis of oligosaccharides, polysaccharides, and glycoconjugates (glycoproteins, glycosaminoglycans, glycolipids, and proteoglycans to name a few). The synthesis of oligo- and polysaccharides as well as glycoconjugates requires the formation of glycosidic bonds, i.e., the formation of a chemical bond between the C1 carbon of a monosaccharide and any hydroxyl oxygen of another monosaccharide or a hydroxyl oxygen of any molecule that bears hydroxyl group, such as a hydroxyamino acid (serine, threonine), a lipid (sphingosine), and phosphatidyl inositol. The glycosidic bond can also be formed between the anomeric C1 carbon of a monosaccharide and the amido nitrogen of asparagine (as, for example, in N-linked glycoproteins) or the nitrogen of a purine or a pyrimidine base (as, for example, in ribo- and deoxyribonucleosides).