An amino sugar is a monosaccharide derivative in which an alcoholic hydroxy group is replaced by an amino group. This commonly occurs at carbon 2, but the position is part of the chemical identity rather than a requirement that all amino sugars share. IUPAC describes these compounds systematically as amino-deoxy derivatives; attachment of nitrogen at the anomeric position belongs to the distinct glycosylamine naming case.[ref]
Nomenclature of Carbohydrates (Recommendations 1996) by Alan D. McNaught. Section 2-Carb-14: amino sugars, general principles and accepted trivial names.
For example, glucosamine is 2-amino-2-deoxy-D-glucose: comparing it with glucose, replace the carbon-2 by . N-acetylglucosamine further modifies that nitrogen with an acetyl group. It remains an amino-sugar derivative; adding that modification does not make it a protein or an amino acid. The useful classification follows the monosaccharide framework and the location of the nitrogen-containing group.[ref]
Nomenclature of Carbohydrates (Recommendations 1996) by Alan D. McNaught. Section 2-Carb-14 and cross-reference to N-substituted derivatives in 2-Carb-25.
These modified building blocks help connect sugar chemistry to biological materials. Hyaluronic acid alternates N-acetylglucosamine with glucuronic acid, so every two-residue repeat contains one amino-sugar derivative. In an ideal segment with 100 complete repeats, there are 100 residues of each type, not 200 N-acetylglucosamine residues.[ref]
Enzymological characterization of the Pasteurella multocida hyaluronic acid synthase by P. L. DeAngelis. Abstract: alternating two-sugar composition and use of two UDP-sugar substrates.
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