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.

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.

Glycosyl hydrolase family 20, catalytic domain. This domain has a TIM barrel fold.

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

Structureand activity of the GH20 beta-N-acetylhexosaminidase from Streptomyces coelicolor A3(2) [Streptomyces coelicolor],4C7D_B Structure and activity of the GH20 beta-N-acetylhexosaminidase from Streptomyces coelicolor A3(2) [Streptomyces coelicolor],4C7F_A Structure and activity of the GH20 beta-N-acetylhexosaminidase from Streptomyces coelicolor A3(2) [Streptomyces coelicolor],4C7F_B Structure and activity of the GH20 beta-N-acetylhexosaminidase from Streptomyces coelicolor A3(2) [Streptomyces coelicolor]

Structureand activity of the GH20 beta-N-acetylhexosaminidase from Streptomyces coelicolor A3(2) [Streptomyces coelicolor]

BT0459[Bacteroides thetaiotaomicron],6Q63_B BT0459 [Bacteroides thetaiotaomicron],6Q63_C BT0459 [Bacteroides thetaiotaomicron]

ChainA, Beta-n-acetylhexosaminidase [Streptomyces plicatus],1HP5_A Chain A, Beta-n-acetylhexosaminidase [Streptomyces plicatus],1JAK_A Chain A, Beta-N-acetylhexosaminidase [Streptomyces plicatus],1M01_A Chain A, Beta-N-acetylhexosaminidase [Streptomyces plicatus],5FCZ_A Chain A, B-N-acetylhexosaminidase [Streptomyces plicatus],5FD0_A Chain A, B-N-acetylhexosaminidase [Streptomyces plicatus]

ChainA, Beta-N-acetylhexosaminidase [Streptomyces plicatus]

Beta-hexosaminidase subunit alpha OS=Entamoeba histolytica OX=5759 GN=HEXA PE=1 SV=2

Beta-hexosaminidase 1 OS=Coccidioides posadasii (strain RMSCC 757 / Silveira) OX=443226 GN=HEX1 PE=1 SV=1