N-terminal catalytic domain of mainly uncharacterized eukaryotic proteins similar to alpha-mannosidases; glycoside hydrolase family 38 (GH38). The subfamily of mainly uncharacterized eukaryotic proteins shows sequence homology with class II alpha-mannosidases (AlphaAMIIs). AlphaAMIIs possess a-1,3, a-1,6, and a-1,2 hydrolytic activity, and catalyze the degradation of N-linked oligosaccharides. The N-terminal catalytic domain of alphaMII adopts a structure consisting of parallel 7-stranded beta/alpha barrel. This subfamily belongs to the GH38 family of retaining glycosyl hydrolases, which employ a two-step mechanism involving the formation of a covalent glycosyl enzyme complex; two carboxylic acids positioned within the active site act in concert: one as a catalytic nucleophile and the other as a general acid/base catalyst.

Glycosyl hydrolases family 38 N-terminal domain. Glycosyl hydrolases are key enzymes of carbohydrate metabolism.

Polysaccharide lyase family 4, domain III. CBM-like is domain III of rhamnogalacturonan lyase (RG-lyase). The full-length protein specifically recognizes and cleaves alpha-1,4 glycosidic bonds between l-rhamnose and d-galacturonic acids in the backbone of rhamnogalacturonan-I, a major component of the plant cell wall polysaccharide, pectin. This domain possesses a jelly roll beta-sandwich fold structurally homologous to carbohydrate binding modules (CBMs), and it carries two sulfate ions and a hexa-coordinated calcium ion.

C-terminal domain of rhamnogalacturonan lyase, a family 4 polysaccharide lyase. The rhamnogalacturonan lyase of the polysaccharide lyase family 4 (RGL4) is involved in the degradation of RG (rhamnogalacturonan) type-I, an important pectic plant cell wall polysaccharide, by cleaving the alpha-1,4 glycoside bond between L-rhamnose and D-galacturonic acids in the backbone of RG type-I through a beta-elimination reaction. RGL4 consists of three domains, an N-terminal catalytic domain, a middle domain with a FNIII type fold and a C-terminal domain with a jelly roll fold. Both the middle and the C-terminal domain are putative carbohydrate binding modules. There are two types of RG lyases, which both cleave the alpha-1,4 bonds of the RG-I main chain (RG chain) through the beta-elimination reaction, but belong to two structurally unrelated polysaccharide lyase (PL) families, 4 and 11.

Glycosyl hydrolases family 38 C-terminal domain. Glycosyl hydrolases are key enzymes of carbohydrate metabolism.