Glükosaminoglükaanid

Glükosaminoglükaanid, often abbreviated as GAGs, are a class of unbranched polysaccharides that are a fundamental component of the extracellular matrix in animals. They are long linear chains composed of repeating disaccharide units. Each disaccharide unit consists of a uronic acid (either glucuronic acid or iduronic acid) and an amino sugar (either glucosamine or galactosamine). The amino group in the amino sugar is typically sulfated, hence the name glükosaminoglükaanid.

The primary function of GAGs is to provide structural support and lubrication in connective tissues, cartilage, skin, and synovial fluid. Their highly hydrophilic nature, due to the abundant negative charges from sulfate and carboxyl groups, allows them to bind large amounts of water. This hydration contributes significantly to the turgor and resilience of tissues. For example, in cartilage, GAGs like chondroitin sulfate and keratan sulfate attract water, which helps to cushion joints and absorb shock. Hyaluronic acid, another important GAG, is a major component of synovial fluid, providing lubrication for joints and contributing to tissue hydration.

Other notable GAGs include heparin and heparan sulfate, which play roles in blood coagulation and cell signaling. Dermatan sulfate is found in skin, tendons, and heart valves. The specific composition and arrangement of GAGs vary depending on their location and function within the body. Disruptions in GAG metabolism or structure can lead to various connective tissue disorders.