Function of Glycosammoglycans. (GAGS)
- They have the special ability to bind large amounts of water, there by producing the gel-like matrix that forms the basis of the body’s ground substance.
- Since they are negatively charged, for example, in bone, glycosaminoglycans attract and tightly bind cattions like ca++, they also take-up Na+ and K+
- GAGs stabilize and support cellular and fibrous components of tissue while helping maintain the water and salt balance of the body.
- Its essential components of the extra cellular matrix, GAGs’ play an important role in mediating cell-cell interactions
- Ground substance is a part of connective tissue, which is a gel like substance containing water, salt, proteins and polysaccharides.
Heparin:
- contains a repeating unit of D-glucuronic and D-gluconsamine, with sulfate groups on some of the hydroxyl and aminx-groups
- It is an important anticoagualtn, prevents the clotting of blood by inhiginting the conversion of prothrombin to throbin. Thrombin is an enzyme that acts on the conversion of plasma fibrinogen into the fibrin.
- It is found in mast cells in lung, liver skin and intestinal mucosa.
Glycoproteins (Mucoproteins)
Glycoprotiens are proteins to which oligosaccharides are covalently attached. They differ from
the glycosaminoglycans in that the length of the glycoproteins carbohydrate chain is relatively
short (usually two to ten sugar residues in length, although they can be longer), whereas it can
be very long in the glycosaminoglycans.
The glycoprotein carbohydrate chains are often branched instead of linear and may or may not
be negatively charged.
For example:
- Glycophorin, a glycoprotein found in human red cell membranes.
- Human gastric glycoprotein (mucin).
- Many protein hormones,receptors are glycoproteins
Proteoglycans
When glycosamnoglycans are attached to a protein molecule the compound is called
proteoglycan [proteoglycans = Glycosaminoglycans + proteins]