The chitobiase of Serratia marcescens is a beta-N-1,4-acetylhexosaminidase with a glycosyl hydrolase family 20 (GH20) domain that hydrolyzes the beta-1,4-glycosidic linkages in oligomers derived from chitin. Chitin is degraded by a two step process: i) a chitinase hydrolyzes the chitin to oligosaccharides and disaccharides such as di-N-acetyl-D-glucosamine and chitobiose, ii) chitobiase then further degrades these oligomers into monomers. This GH20 domain family includes an N-acetylglucosamidase (GlcNAcase A) from Pseudoalteromonas piscicida and an N-acetylhexosaminidase (SpHex) from Streptomyces plicatus. SpHex lacks the C-terminal PKD (polycystic kidney disease I)-like domain found in the chitobiases. 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 hydrolases family 35.

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

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

A functionally uncharacterized subgroup of the Glycosyl hydrolase family 20 (GH20) catalytic domain found in proteins similar to the chitobiase of Serratia marcescens, a beta-N-1,4-acetylhexosaminidase that hydrolyzes the beta-1,4-glycosidic linkages in oligomers derived from chitin. Chitin is degraded by a two step process: i) a chitinase hydrolyzes the chitin to oligosaccharides and disaccharides such as di-N-acetyl-D-glucosamine and chitobiose, ii) chitobiase then further degrades these oligomers into monomers. This subgroup lacks the C-terminal PKD (polycystic kidney disease I)-like domain found in the chitobiases. 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.

GalactanaseBT0290 [Bacteroides thetaiotaomicron VPI-5482]

Crystalstructure of a beta-galactosidase from Bacteroides thetaiotaomicron [Bacteroides thetaiotaomicron VPI-5482]

ChainA, Beta-galactosidase [Niallia circulans],4MAD_B Chain B, Beta-galactosidase [Niallia circulans]

Crystalstructure of streptococcal beta-galactosidase in complex with galactose [Streptococcus pneumoniae TIGR4],4E8C_B Crystal structure of streptococcal beta-galactosidase in complex with galactose [Streptococcus pneumoniae TIGR4],4E8D_A Crystal structure of streptococcal beta-galactosidase [Streptococcus pneumoniae TIGR4],4E8D_B Crystal structure of streptococcal beta-galactosidase [Streptococcus pneumoniae TIGR4]

Crystalstructure of human beta-galactosidase mutant I51T in complex with Galactose [Homo sapiens],3WF3_B Crystal structure of human beta-galactosidase mutant I51T in complex with Galactose [Homo sapiens],3WF3_C Crystal structure of human beta-galactosidase mutant I51T in complex with Galactose [Homo sapiens],3WF3_D Crystal structure of human beta-galactosidase mutant I51T in complex with Galactose [Homo sapiens],3WF4_A Crystal structure of human beta-galactosidase mutant I51T in complex with 6S-NBI-DGJ [Homo sapiens],3WF4_B Crystal structure of human beta-galactosidase mutant I51T in complex with 6S-NBI-DGJ [Homo sapiens],3WF4_C Crystal structure of human beta-galactosidase mutant I51T in complex with 6S-NBI-DGJ [Homo sapiens],3WF4_D Crystal structure of human beta-galactosidase mutant I51T in complex with 6S-NBI-DGJ [Homo sapiens]

Beta-galactosidase OS=Xanthomonas manihotis OX=43353 GN=bga PE=1 SV=1

Beta-galactosidase OS=Homo sapiens OX=9606 GN=GLB1 PE=1 SV=2

Beta-galactosidase OS=Macaca fascicularis OX=9541 GN=GLB1 PE=2 SV=1

Beta-galactosidase-1-like protein OS=Macaca fascicularis OX=9541 GN=GLB1L PE=2 SV=1

Beta-galactosidase OS=Pongo abelii OX=9601 GN=GLB1 PE=2 SV=1