Nglycolylneuraminic

N-glycolylneuraminic acid (Neu5Gc) is a form of sialic acid—a nine-carbon acidic sugar that caps glycoproteins and glycolipids on the surfaces of many mammalian cells. Neu5Gc differs from N-acetylneuraminic acid (Neu5Ac) by an extra hydroxyl group on the N-acyl side chain, giving rise to the N-glycolyl substituent.

In most mammals, Neu5Gc is produced from Neu5Ac by the enzyme CMAH (CMP-N-acetylneuraminic acid hydroxylase). Humans have a nonfunctional CMAH gene due to a historic mutation, so human cells predominantly present Neu5Ac rather than Neu5Gc on surface glycoconjugates.

Neu5Gc is present in most non-human mammalian foods, especially red meat and dairy. Humans can incorporate trace amounts of Neu5Gc into tissues from the diet, displaying it on glycoproteins and glycolipids. Many humans carry circulating antibodies against Neu5Gc, reflecting exposure to non-human sialic acids.

The coexistence of dietary Neu5Gc and anti-Neu5Gc antibodies has been proposed to promote chronic inflammation, sometimes called xenosialitis, and has been investigated for possible links to cancer and cardiovascular disease. Evidence is inconclusive, and most insights come from CMAH-knockout mouse models and in vitro studies.

Neu5Gc remains a topic of interest in glycoimmunology, glycobiology, and xenotransplantation research.