Exoskeletons and Exhalation

Chitin — the second-most abundant biologic polymer, after cellulose — is a tough, cross-linked polysaccharide (see Figure 1) found in the exoskeleton of insects and crustaceans, the cell wall of fungi, and the pharynx, microfilarial sheath, and egg of parasitic worms (helminths). The presence of chitin in so many organisms that can function as pathogens toward plants and higher animals makes it an attractive target for host recognition and enzymatic attack. Indeed, plants are well known to express chitinases in response to the presence of chitin-containing pathogens. More recently, chitinases and chitinase-like proteins have been identified in the genomes of mammals . . .