Acidglycan

Acidglycan is a term occasionally used to describe acidic glycans, a class of polysaccharides bearing a high density of negative charges from uronic acid residues and sulfate groups. In contemporary biochemistry, the preferred designation is glycosaminoglycan (GAG); acidglycan is largely synonymous with this group in historical or non-specialist usage.

Glycosaminoglycans are long, unbranched chains made of repeating disaccharides. Each disaccharide usually includes an amino sugar (such as N-acetylglucosamine or N-acetylgalactosamine) paired with a uronic acid (glucuronic or iduronic acid), with sulfation adding further negative charge. Hyaluronic acid is non-sulfated, while other GAGs—heparan sulfate, heparin, chondroitin sulfate, dermatan sulfate, and keratan sulfate—exhibit diverse sulfation patterns. GAGs typically attach to core proteins to form proteoglycans in the extracellular matrix and on cell surfaces.

Biosynthesis occurs in the Golgi apparatus. The repeating disaccharide units are assembled on a linker region and then modified by sulfotransferases and epimerases. Degradation involves lysosomal enzymes and extracellular hydrolases; defects in breakdown cause mucopolysaccharidoses, a group of lysosomal storage disorders.

Functions of acidic glycans include providing structural integrity to tissues, lubricating joints, and regulating signaling by binding growth factors, chemokines, and cytokines. They influence cell adhesion, migration, and development, as well as inflammation.

Because the standard term is glycosaminoglycan, acidglycan is rarely used in modern literature beyond historical context or introductory explanations.