Endo-beta-N-acetylglucosaminidases are bacterial chitinases that hydrolyze the chitin core of various asparagine (N)-linked glycans and glycoproteins. The endo-beta-N-acetylglucosaminidases have a glycosyl hydrolase family 18 (GH18) catalytic domain. Some members also have an additional C-terminal glycosyl hydrolase family 20 (GH20) domain while others have an N-terminal domain of unknown function (pfam08522). Members of this family include endo-beta-N-acetylglucosaminidase S (EndoS) from Streptococcus pyogenes, EndoF1, EndoF2, EndoF3, and EndoH from Flavobacterium meningosepticum, and EndoE from Enterococcus faecalis. EndoS is a secreted endoglycosidase from Streptococcus pyogenes that specifically hydrolyzes the glycan on human IgG between two core N-acetylglucosamine residues. EndoE is a secreted endoglycosidase, encoded by the ndoE gene in Enterococcus faecalis, that hydrolyzes the glycan on human RNase B.

Alpha amylase catalytic domain found in cyclomaltodextrinases and related proteins. Cyclomaltodextrinase (CDase; EC3.2.1.54), neopullulanase (NPase; EC 3.2.1.135), and maltogenic amylase (MA; EC 3.2.1.133) catalyze the hydrolysis of alpha-(1,4) glycosidic linkages on a number of substrates including cyclomaltodextrins (CDs), pullulan, and starch. These enzymes hydrolyze CDs and starch to maltose and pullulan to panose by cleavage of alpha-1,4 glycosidic bonds whereas alpha-amylases essentially lack activity on CDs and pullulan. They also catalyze transglycosylation of oligosaccharides to the C3-, C4- or C6-hydroxyl groups of various acceptor sugar molecules. Since these proteins are nearly indistinguishable from each other, they are referred to as cyclomaltodextrinases (CMDs). This group of CMDs is mainly bacterial. The Alpha-amylase family comprises the largest family of glycoside hydrolases (GH), with the majority of enzymes acting on starch, glycogen, and related oligo- and polysaccharides. These proteins catalyze the transformation of alpha-1,4 and alpha-1,6 glucosidic linkages with retention of the anomeric center. The protein is described as having 3 domains: A, B, C. A is a (beta/alpha) 8-barrel; B is a loop between the beta 3 strand and alpha 3 helix of A; C is the C-terminal extension characterized by a Greek key. The majority of the enzymes have an active site cleft found between domains A and B where a triad of catalytic residues (Asp, Glu and Asp) performs catalysis. Other members of this family have lost the catalytic activity as in the case of the human 4F2hc, or only have 2 residues that serve as the catalytic nucleophile and the acid/base, such as Thermus A4 beta-galactosidase with 2 Glu residues (GH42) and human alpha-galactosidase with 2 Asp residues (GH31). The family members are quite extensive and include: alpha amylase, maltosyltransferase, cyclodextrin glycotransferase, maltogenic amylase, neopullulanase, isoamylase, 1,4-alpha-D-glucan maltotetrahydrolase, 4-alpha-glucotransferase, oligo-1,6-glucosidase, amylosucrase, sucrose phosphorylase, and amylomaltase.

ChainA, ENDO-BETA-N-ACETYLGLUCOSAMINIDASE H, ENDO H [Streptomyces plicatus]

ChainA, Endo-beta-N-acetylglucosaminidase H [Streptomyces plicatus],6VE1_B Chain B, Endo-beta-N-acetylglucosaminidase H [Streptomyces plicatus],6VE1_C Chain C, Endo-beta-N-acetylglucosaminidase H [Streptomyces plicatus],6VE1_D Chain D, Endo-beta-N-acetylglucosaminidase H [Streptomyces plicatus]

ChainA, ENDO-BETA-N-ACETYLGLUCOSAMINIDASE H [Streptomyces plicatus],1C90_B Chain B, ENDO-BETA-N-ACETYLGLUCOSAMINIDASE H [Streptomyces plicatus]

ChainA, ENDO-BETA-N-ACETYLGLUCOSAMINIDASE H [Streptomyces plicatus]

ChainA, ENDO-BETA-N-ACETYLGLUCOSAMINIDASE H [Streptomyces plicatus]

Endo-beta-N-acetylglucosaminidase H OS=Streptomyces plicatus OX=1922 PE=1 SV=1

Endo-beta-N-acetylglucosaminidase OS=Flavobacterium sp. (strain SK1022) OX=148444 PE=1 SV=2

Endo-beta-N-acetylglucosaminidase F1 OS=Elizabethkingia meningoseptica OX=238 GN=endOF1 PE=1 SV=1