Beta-galactosidase. This group of beta-galactosidase enzymes belong to the glycosyl hydrolase 42 family. The enzyme catalyzes the hydrolysis of terminal, non-reducing terminal beta-D-galactosidase residues.

Beta-galactosidase GanA [Carbohydrate transport and metabolism].

Beta-galactosidase trimerisation domain. This is non catalytic domain B of beta-galactosidase enzymes belong to the glycosyl hydrolase 42 family. This domain is related to glutamine amidotransferase enzymes, but the catalytic residues are replaced by non functional amino acids. This domain is involved in trimerisation.

Glycosyl hydrolase family 43 protein such as Bacteroides thetaiotaomicron VPI-5482 arabinofuranosidase Bt3655. This glycosyl hydrolase family 43 (GH43)-like family includes the characterized arabinofuranosidases (EC 3.2.1.55): Bacteroides thetaiotaomicron VPI-5482 (Bt3655;BT_3655) and Penicillium chrysogenum 31B Abf43B, as well as Bifidobacterium adolescentis ATCC 15703 beta-xylosidase (EC 3.2.1.37) BAD_1527. It belongs to the glycosyl hydrolase clan F (according to carbohydrate-active enzymes database (CAZY)) which includes family 43 (GH43) and 62 (GH62) families. GH43 includes enzymes with beta-xylosidase (EC 3.2.1.37), beta-1,3-xylosidase (EC 3.2.1.-), alpha-L-arabinofuranosidase (EC 3.2.1.55), arabinanase (EC 3.2.1.99), xylanase (EC 3.2.1.8), endo-alpha-L-arabinanases (beta-xylanases) and galactan 1,3-beta-galactosidase (EC 3.2.1.145) activities. GH43 are inverting enzymes (i.e. they invert the stereochemistry of the anomeric carbon atom of the substrate) that have an aspartate as the catalytic general base, a glutamate as the catalytic general acid and another aspartate that is responsible for pKa modulation and orienting the catalytic acid. Many GH43 enzymes display both alpha-L-arabinofuranosidase and beta-D-xylosidase activity using aryl-glycosides as substrates. A common structural feature of GH43 enzymes is a 5-bladed beta-propeller domain that contains the catalytic acid and catalytic base. A long V-shaped groove, partially enclosed at one end, forms a single extended substrate-binding surface across the face of the propeller.

A4 beta-galactosidase middle domain: a type 1 glutamine amidotransferase (GATase1)-like domain. A4 beta-galactosidase middle domain: a type 1 glutamine amidotransferase (GATase1)-like domain. This group includes proteins similar to beta-galactosidase from Thermus thermophilus. Beta-Galactosidase hydrolyzes the beta-1,4-D-galactosidic linkage of lactose, as well as those of related chromogens, o-nitrophenyl-beta-D-galactopyranoside (ONP-Gal) and 5-bromo-4-chloro-3-indolyl-beta-D-galactoside (X-gal). This A4 beta-galactosidase middle domain lacks the catalytic triad of typical GATase1 domains. The reactive Cys residue found in the sharp turn between a beta strand and an alpha helix termed the nucleophile elbow in typical GATase1 domains is not conserved in this group.

PolyextremophilicBeta-galactosidase from the Antarctic haloarchaeon Halorubrum lacusprofundi [Halorubrum lacusprofundi ATCC 49239]

Crystalstructure of Thermus thermophilus A4 beta-galactosidase [Thermus thermophilus],1KWK_A Crystal structure of Thermus thermophilus A4 beta-galactosidase in complex with galactose [Thermus thermophilus]

ChainA, beta-galactosidase [Marinomonas sp. ef1]

3Dstructure of Gan42B, a GH42 beta-galactosidase from G. [Geobacillus stearothermophilus],4OIF_B 3D structure of Gan42B, a GH42 beta-galactosidase from G. [Geobacillus stearothermophilus],4OIF_C 3D structure of Gan42B, a GH42 beta-galactosidase from G. [Geobacillus stearothermophilus]

3Dstructure of the E323A catalytic mutant of Gan42B, a GH42 beta-galactosidase from G. stearothermophilus [Geobacillus stearothermophilus],4OJY_B 3D structure of the E323A catalytic mutant of Gan42B, a GH42 beta-galactosidase from G. stearothermophilus [Geobacillus stearothermophilus],4OJY_C 3D structure of the E323A catalytic mutant of Gan42B, a GH42 beta-galactosidase from G. stearothermophilus [Geobacillus stearothermophilus]

Beta-galactosidase BgaH OS=Haloferax lucentense (strain DSM 14919 / JCM 9276 / NCIMB 13854 / Aa 2.2) OX=1230452 GN=bgaH PE=1 SV=2

Beta-galactosidase Bga OS=Halorubrum lacusprofundi (strain ATCC 49239 / DSM 5036 / JCM 8891 / ACAM 34) OX=416348 GN=Hlac_2868 PE=1 SV=1

Beta-galactosidase OS=Thermus thermophilus OX=274 PE=1 SV=1

Beta-galactosidase BgaA OS=Thermus sp. OX=275 GN=bgaA PE=1 SV=1

Beta-galactosidase BgaA OS=Thermus sp. OX=275 GN=bgaA PE=1 SV=1