glikozaminoglikany

Glikozaminoglikany, often abbreviated as GAGs, are a diverse class of linear unbranched polysaccharides found in virtually all animal tissues. They are composed of repeating disaccharide units, where one sugar is always an amino sugar (either N-acetylglucosamine or N-acetylgalactosamine) and the other is usually a uronic acid (glucuronic acid or iduronic acid), with the exception of keratan sulfate, which contains galactose instead of a uronic acid. GAGs are highly negatively charged due to the presence of sulfate and carboxyl groups, which causes them to repel each other and adopt extended conformations. This negative charge is crucial for their function, as it allows them to bind large amounts of water and cations, contributing to the viscosity and hydration of tissues.

GAGs play essential roles in various biological processes. They are major components of the extracellular matrix, providing structural support and lubrication to connective tissues, cartilage, tendons, and the synovial fluid in joints. Their ability to attract water contributes to tissue turgor and shock absorption. Furthermore, GAGs are involved in cell signaling, cell adhesion, and wound healing. They can interact with growth factors and other signaling molecules, influencing cellular behavior. Different types of GAGs, such as hyaluronic acid, chondroitin sulfate, dermatan sulfate, heparan sulfate, and keratan sulfate, have distinct structures and are found in specific locations and tissues, reflecting their specialized functions. Defects in GAG synthesis or degradation can lead to a group of metabolic disorders known as mucopolysaccharidoses.