Glycosaminoglycan (GAG)

A class of long, unbranched polysaccharide chains composed of repeating disaccharide units, typically containing an amino sugar (N-acetylglucosamine or N-acetylgalactosamine) and a uronic acid (glucuronic acid or iduronic acid). Glycosaminoglycans are major structural components of the extracellular matrix. Key examples include hyaluronic acid (a non-sulfated GAG found in synovial fluid and skin), chondroitin sulfate, and heparan sulfate. Sodium hyaluronate (Section 51) is the sodium salt of the glycosaminoglycan hyaluronic acid.