Chitin binding domain.

GH18 domain of Chitinase D (ChiD). ChiD, a chitinase found in Bacillus circulans, hydrolyzes the 1,4-beta-linkages of N-acetylglucosamine in chitin and chitodextrins. The domain architecture of ChiD includes a catalytic glycosyl hydrolase family 18 (GH18) domain, a chitin-binding domain, and a fibronectin type III domain. The chitin-binding and fibronectin type III domains are located either N-terminal or C-terminal to the catalytic domain. This family includes exochitinase Chi36 from Bacillus cereus.

Hevein or type 1 chitin binding domain. Hevein or type 1 chitin binding domain (ChtBD1), a lectin domain found in proteins from plants and fungi that bind N-acetylglucosamine, plant endochitinases, wound-induced proteins such as hevein, a major IgE-binding allergen in natural rubber latex, and the alpha subunit of Kluyveromyces lactis killer toxin. This domain is involved in the recognition and/or binding of chitin subunits; it typically occurs N-terminal to glycosyl hydrolase domains in chitinases, together with other carbohydrate-binding domains, or by itself in tandem-repeat arrangements.

Glycosyl hydrolases family 18.

This conserved domain family includes xylanase inhibitor Xip-I, and the class III plant chitinases such as hevamine, concanavalin B, and PPL2, all of which have a glycosyl hydrolase family 18 (GH18) domain. Hevamine is a class III endochitinase that hydrolyzes the linear polysaccharide chains of chitin and peptidoglycan and is important for defense against pathogenic bacteria and fungi. PPL2 (Parkia platycephala lectin 2) is a class III chitinase from Parkia platycephala seeds that hydrolyzes beta(1-4) glycosidic bonds linking 2-acetoamido-2-deoxy-beta-D-glucopyranose units in chitin.