| Primary Identifier | IPR001223 | Type | Domain |
| Short Name | Glyco_hydro18_cat |
| description | O-Glycosyl hydrolases () are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrateand a non-carbohydrate moiety. A classification system for glycosyl hydrolases, based on sequence similarity, has led to the definition of 85 different families [, ]. This classification is available on the CAZy (CArbohydrate-Active EnZymes) website.The glycosyl hydrolases family 18 (GH18) is widely distributed in all kingdoms and contains hydrolytic enzymes with chitinase or endo-N-acetyl-beta-D-glucosaminidase (ENGase) activity as well as chitinase-like lectins (chi-lectins/proteins (CLPs). Chitinases () are hydrolytic enzymes that cleave the beta-1,4-bond releasing oligomeric, dimeric (chitobiose) or monomeric (N-actetylglucosamine, GlcNAc) products. ENGases () hydrolyze the beta-1,4 linkage in the chitobiose core of N-linked glycans from glycoproteins leaving one GlcNAc residue on the substrate. CLPs do not display chitinase activity but some of them have been reported to have specific functions and carbohydrate binding property []. This family also includes glycoproteins from mammals, such as oviduct-specific glycoproteins.The catalytic domain of GH18s has a common (beta/alpha)8 triosephosphate isomerase (TIM)-barrel structure, which consists of a barrel-like framework made from eight internal parallel β-strands that are alternately connected by eight exterior α-helices. The active site motif DxxDxDxE is essential for the activity of the GH18 catalytic domain. [, , ]. |
