mannosamine

Mannosamine refers to a class of amino sugars, specifically 2-amino-2-deoxy-D-mannose. It is an aldohexose derivative in which the C-2 hydroxyl group of mannose is replaced by an amino group. The naturally occurring form is the D enantiomer, with L-mannosamine as its mirror image.

In biology, mannosamine is best known as a precursor to sialic acids. Through acetylation, it forms N-acetylmannosamine (ManNAc), a key intermediate in the biosynthesis of N-acetylneuraminic acid (Neu5Ac), the most common sialic acid. In organisms that produce sialic acids, the pathway funnels ManNAc into the series of enzymatic steps that ultimately generate Neu5Ac, which is commonly found at the termini of glycoprotein and glycolipid chains. Free mannosamine is not a major circulating metabolite in mammals, but it can occur in small amounts in some bacteria and plants, and it can be prepared synthetically in the laboratory.

Beyond its biological role, mannosamine and its derivatives are used in research and development. They serve as substrates and reagents in studies of glycosyltransferases, in the exploration of sialic acid biosynthesis, and as starting materials for synthesizing sialic acid-containing glycoconjugates and related compounds. Related compounds include N-acetylmannosamine (ManNAc) and the broader family of sialic acids.

See also monosaccharides, amino sugars, sialic acid biosynthesis.