Chitin

Chitin (IPA: ) is one of the main components in the cell walls of fungi, the exoskeletons of insects and other arthropods, and in some other animals. It is a polysaccharide; it is constructed from units of acetylglucosamine (more completely, N-acetyl-D-glucos-2-amine). These are linked together in β-1,4 fashion (in a similar manner to the glucose units which form cellulose). In effect chitin may be described as cellulose with one hydroxyl group on each monomer replaced by an acetyl amine group. This allows for increased hydrogen bonding between adjacent polymers, giving the polymer increased strength.

"Chitin" and "chiton" (a marine animal) both derive from the same Greek word meaning "tunic", referring to the protective shell. In its unmodified form, it is translucent, pliable and resilient, and quite tough. In arthropods, however, it is frequently modified, by being embedded in a hardened proteinaceous matrix, which forms much of the exoskeleton. The difference between unmodified and modified chitinous exoskeleton can be seen by comparing the body wall of a caterpillar to a beetle, for example.

Chitin is an unusual substance as it is a natually occurring polymer. Its breakdown is conducted by bacteria which have receptors to simple sugars from the decomposition of chitin. If chitin is detected they then produce enzymes to digest the chitin by reducing it to simple sugars and ammonia.

Uses in medicine

Chitin's properties as a tough, and strong material make it favourable for use in surgical thread. Its biodegradibility also means it wears away with time as the wound heals.

Chitin and the immune system

Chitin also has some unusual properties in that it accelerated healing in wounds in humans. It is closly related to chitosan (a more water-soluble derivative of chitin) and the immune system of plants and animals.

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Biochemistry | Polysaccharides

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Uses in medicine

Chitin and the immune system

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