Glycosyl hydrolase family 20 (GH20) catalytic domain of N-acetyl-beta-D-glucosaminidase (GcnA, also known as BhsA) and related proteins. GcnA is an exoglucosidase which cleaves N-acetyl-beta-D-galactosamine (NAG) and N-acetyl-beta-D-galactosamine residues from 4-methylumbelliferylated (4MU) substrates, as well as cleaving NAG from chito-oligosaccharides (i.e. NAG polymers). In contrast, sulfated forms of the substrate are unable to be cleaved and act instead as mild competitive inhibitors. Additionally, the enzyme is known to be poisoned by several first-row transition metals as well as by mercury. GcnA forms a homodimer with subunits comprised of three domains, an N-terminal zincin-like domain, this central catalytic GH20 domain, and a C-terminal alpha helical domain. The GH20 hexosaminidases are thought to act via a catalytic mechanism in which the catalytic nucleophile is not provided by solvent or the enzyme, but by the substrate itself.

Beta-N-acetylhexosaminidases of glycosyl hydrolase family 20 (GH20) catalyze the removal of beta-1,4-linked N-acetyl-D-hexosamine residues from the non-reducing ends of N-acetyl-beta-D-hexosaminides including N-acetylglucosides and N-acetylgalactosides. These enzymes are broadly distributed in microorganisms, plants and animals, and play roles in various key physiological and pathological processes. These processes include cell structural integrity, energy storage, cellular signaling, fertilization, pathogen defense, viral penetration, the development of carcinomas, inflammatory events and lysosomal storage disorders. The GH20 enzymes include the eukaryotic beta-N-acetylhexosaminidases A and B, the bacterial chitobiases, dispersin B, and lacto-N-biosidase. The GH20 hexosaminidases are thought to act via a catalytic mechanism in which the catalytic nucleophile is not provided by the solvent or the enzyme, but by the substrate itself.

N-acetyl-beta-hexosaminidase [Carbohydrate transport and metabolism].

Glycosyl hydrolase family 20, domain 2. This domain has a zincin-like fold.

Glycosyl hydrolase family 20 (GH20) catalytic domain of dispersin B (DspB), lacto-N-biosidase (LnbB) and related proteins. Dispersin B is a soluble beta-N-acetylglucosamidase found in bacteria that hydrolyzes the beta-1,6-linkages of PGA (poly-beta-(1,6)-N-acetylglucosamine), a major component of the extracellular polysaccharide matrix. Lacto-N-biosidase hydrolyzes lacto-N-biose (LNB) type I oligosaccharides at the nonreducing terminus to produce lacto-N-biose as part of the GNB/LNB (galacto-N-biose/lacto-N-biose I) degradation pathway. The lacto-N-biosidase from Bifidobacterium bifidum has this GH20 domain, a carbohydrate binding module 32, and a bacterial immunoglobulin-like domain 2, as well as a YSIRK signal peptide and a G5 membrane anchor at the N and C termini, respectively. The GH20 hexosaminidases are thought to act via a catalytic mechanism in which the catalytic nucleophile is not provided by solvent or the enzyme, but by the substrate itself.

Thecrystal structure of beta-N-acetylhexosaminidase from Bacteroides fragilis NCTC 9343 [Bacteroides fragilis NCTC 9343],4PYS_B The crystal structure of beta-N-acetylhexosaminidase from Bacteroides fragilis NCTC 9343 [Bacteroides fragilis NCTC 9343]

CrystalStructure of Beta-N-Acetylhexosaminidase from Arthrobacter aurescens [Paenarthrobacter aurescens TC1]

crystalstructure of a beta-N-acetylhexosaminidase [Akkermansia muciniphila ATCC BAA-835],6JEA_A crystal structure of a beta-N-acetylhexosaminidase [Akkermansia muciniphila ATCC BAA-835],6JEB_A crystal structure of a beta-N-acetylhexosaminidase [Akkermansia muciniphila ATCC BAA-835]

ChainA, Beta-N-acetylhexosaminidase [Bacteroides thetaiotaomicron],7DVA_A Chain A, Beta-N-acetylhexosaminidase [Bacteroides thetaiotaomicron],7DVA_B Chain B, Beta-N-acetylhexosaminidase [Bacteroides thetaiotaomicron]

ChainA, Beta-N-acetylhexosaminidase [Bacteroides thetaiotaomicron],7DVB_B Chain B, Beta-N-acetylhexosaminidase [Bacteroides thetaiotaomicron],7DVB_C Chain C, Beta-N-acetylhexosaminidase [Bacteroides thetaiotaomicron],7DVB_D Chain D, Beta-N-acetylhexosaminidase [Bacteroides thetaiotaomicron]

Beta-hexosaminidase Amuc_2018 OS=Akkermansia muciniphila (strain ATCC BAA-835 / DSM 22959 / JCM 33894 / BCRC 81048 / CCUG 64013 / CIP 107961 / Muc) OX=349741 GN=Amuc_2018 PE=1 SV=1

Beta-hexosaminidase OS=Porphyromonas gingivalis (strain ATCC BAA-308 / W83) OX=242619 GN=nahA PE=3 SV=2

Beta-hexosaminidase OS=Vibrio vulnificus OX=672 GN=hex PE=3 SV=1

Beta-hexosaminidase B OS=Pseudoalteromonas piscicida OX=43662 GN=nag096 PE=3 SV=1

Hexosaminidase D OS=Mus musculus OX=10090 GN=Hexd PE=1 SV=1