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A sugar in which one or more nonglycosidic hydroxyl groups is replaced by an amino or substituted amino group. The most abundant example is d -glucosamine (2-amino-2-deoxy- d -glucose) [see illustration].
A linear polymer of N-acetyl- d -glucosamine is widely distributed as chitin, the exoskeletal material of arthropods. The glycoproteins of higher animals, which are components of the proteoglycans of cartilage and skin, consist of polysaccharides that are generally sulfated and have N-acetylated glucosamine or galactosamine alternating with a uronic acid.
Amino sugars are important constituents of glycoproteins and oligosaccharides involved in biological recognition. Amino sugars of the greatest structural diversity are found in microorganisms as constituents of cell walls, in antigenic carbohydrates produced at the cell surface, and as antibiotic substances secreted from the cell. Streptomycin is the first demonstrated example of numerous amino-sugar-containing antibiotics produced notably by Actinomycetes (bacteria). See Chitin, Glycoprotein, Oligosaccharide, Polysaccharide