Question

76.Glycosaminoglycans: diversity of structure and tissue distribution.

(please more explanatıon Im medicine student) thank you...

Answer 1

Glycosaminoglycans also known as mucopolysaccharides, are made up of repeating units of disaccharides containing amino sugars (glucosamine or galactosamine) and uronic acids (glucuronic acid or iduronic acid). Amino sugars are further acetylated and sulfated. The major glycosaminoglycans are:-

HYALURONIC ACID: It contains about 200 to 20000 disaccharide units of D-glucuronic acid and N-acetyl-D-glucosamine held together by beta-1,3-glycosidic bonds. it occurs in the ground substance of synovial fluid of joints, cartilage and vitreous body of the eye. It acts as a lubricant in the skeletal joints. It also occurs as a gel around the ovum. It is also present in plasma membranes acting as a receptor, participates in cell adhesion, and in Cell to cell interaction. It determines the the charge selectiveness of renal glomerulus.

CHONDROITIN SULFATE: It is distributed in the ground substance of cartilage, bone, tendons and joints. It is specifically located at the sites of calcification in endochondral bone. its presence in cartilage contributes to its compressibility and weight bearing capacity. It acts as a lubricant in the skeletal joints.

KERATAN SULFATE (I AND II) : It is found in the cornea, tendons and cartilage. It is the only glycosaminoglycan that it does not contain uronic acid residue. Along with the dermatan sulfate it plays a critical role in corneal transparency.

HEPARIN AND HEPARAN SULFATE: Heparin is an anticoagulant. It is used to prevent intravascular clotting in thromboembolism. Heparin causes the release of enzyme lipoprotein lipase. it is present in the liver, lungs, spleen and monocytes.

DERMATAN SULFATE: It mostly occurs in the skin. It is also present in blood vessels, heart valves, cornea and sclera. In sclera, it is responsible for maintaining the shape of the eyeball.