Hyaluronic acid is made up of repeating units of D-glucuronic acid and N-acetyl glucosamine (Figure 2.19). When it is subjected to hydrolysis, it forms D-glucosamine, D-glucuronic acid, and acetic acid. It is also hydrolysed by the enzyme hyaluronidase present in spleen and testicular tissues. The main action of this enzyme is to reduce the viscosity…

Occurrence Hyaluronic acid is a viscous substance that is present as a ground substance in connective tissues. It is also found in skin, synovial fluid, vitreous humour of the eyes, and umbilical cord. Hyaluronic acid mainly functions as a lubricant and shock absorber. It is the only GAG that is not attached to protein and also…

Mucopolysaccharides are also known as GAGs. Uronic acid is either gluconic acid or its epimer L-iduronic acid; an exception is the keratin sulphate where sulphate galactose is present instead of acidic sugar. The amino sugar is either D-glucosamine or D-galactosamine, in which the amino group is usually acetylated. The amino sugar may be sulphated in…

Heteropolysaccharide is a kind of polysaccharide. Heteropolysaccharides containing the repeating units of amino sugars and uronic acid are known as mucopolysaccharides or GAGs. Glycoproteins or mucoproteins are proteins with carbohydrate units made up of a short (2–10 sugar residues) chain. Proteoglycans is a heteropolysaccharide connected to a polypeptide. Glycolipids are lipids containing a carbohydrate group.

Chitin is made up of N-acetyl D-glucosamine linked by α(1 → 4) glycosidic linkages (Figure 2.18). The structure is very similar to cellulose, except that an acetylated amino group is present in the C-2 position. Figure 2.18 Structure of Chitin

Occurrence Chitin is present in the exoskeleton of invertebrates such as crabs, lobsters, and insects.

Dextran has a molecular weight of approximately 75,000. It is used as a plasma extender when taken intravenously. It increases the blood volume when there is a loss of blood.

Dextran is a polysaccharide composed of glucose units. The only difference between dextrans and dextrins is in the structure. Dextrans are made up of a number of D-glucose molecules, having α(1 → 6), α(1 → 4), and α(1 → 3) glycosidic linkages (Figure 2.17). Figure 2.17 Structure of Dextran

It consists of galactose, which is sulphated as represented in Figure 2.16. It is applied as a laxative in constipation. Purified agar is used as a bacterial culture medium. Figure 2.16 Structure of Agarose

Occurrence Agar is generally present in sea weeds.