Occurrence and Significance

Abstract

Many different monosaccharidic compounds are present as constituents of a variety of substances in higher and lower plants, animals, and microorganisms. Among the naturally occurring compounds that contain monosaccharidic components are antibiotics, glycolipids (see Chap. 7), glycosphingolipids (see Chap. 7), glycoproteins (see Chap. 8), C-glycosyl compounds, glycosyl esters, lipopolysaccharides (see Chap. 7), nucleosides, nucleotides, oligosaccharides (see Chap. 5), peptidoglycans (see Chap. 6.1), glycosides of a variety of substances in algae and higher plants, polysaccharides (see Chap. 6), protein polysaccharides (see Chap. 6), proteoglycans (see Chap. 6.1), and teichoic acids. Among the types of monosaccharidic constituents found in one or more of these classes of compounds are alditols, aldoses, aminodeoxysugars, anhydrosugars, branchedchain sugars, deoxysugars, ketoses, thiosugars, and uronic acids. These monosacccharidic constituents usually contain five or six carbon atoms, i.e., are pentoses or hexoses, respectively. The monosaccharide units in these compounds are joined to other constituents by glycosidic, glycosylamine, or ester linkages, with the former being in an overwhelming majority.