Sialic acid

A compound formed from mannosamine and pyruvate with the molecular formula: C11H19NO9 Sialic acids are mono- or diacetylated derivatives of neuraminic acid.

Sialic acids are components of glycoproteins, glycosaminoglycans, glycolipids (gangliosides). Sialic acids are released by their enzymatic degradation within lysosomes. Physiologically, they are transported out of the lysosome through the membrane of the lysosome by the anion transport protein sialin.

The N-acylneuraminic acid serves as the terminal saccharide member of the oligosaccharide chains of sialoglycoproteins. It protects them against degradation by hepatocytes.

In sialic acid storage disease (sialinosis), mutations in the sialin-encoding gene lead to a functional impairment or loss of the sialin transport protein