The Bacteroides thetaiotaomicron protein represented by pdb structure 3CO4 is an uncharacterized bacterial member of the family 18 glycosyl hydrolases with homologs found in Flavobacterium, Stigmatella, and Pseudomonas.

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.

Chitinase [Carbohydrate transport and metabolism]

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.