Isolation and characterization of an endo-beta-galactosidase from Bacteroides fragilis.
Six strains of Bacteroides fragilis were examined and all found to produce endo-beta-galactosidase, an enzyme that hydrolyses internal beta-galactosidic linkages of oligosaccharides belonging to the poly-N-acetyl-lactosamine series, with the common structure GlcNAc beta 1 leads to 3Gal beta 1 leads to 4GlcNAc/Glc. The enzyme was produced without the addition of an inducer such as keratan sulphate. It was purified 7000-fold from the culture supernatant and obtained with a yield 4-10-fold greater than from sources described previously. The specificity of the enzyme towards bovine corneal keratan sulphate, milk oligosaccharides and the glycolipids lacto-N-neotetraosylceramide and lacto-N-tetraosylceramide closely resembled that of the endo-beta-galactosidase isolated from Escherichia freundii. A novel observation was that both enzymes hydrolysed the type 2 sequence, Gal beta 1 leads to 4GlcNAc beta 1 leads to 3Gal beta 1 leads to 4Glc, at about twice the rate of the type 1 isomer, Gal beta 1 leads to 3GlcNAc beta 1 leads to 3Gal beta 1 leads to 4Glc. Because of the ease of purification of the enzyme and high yield in the absence of contaminating glycosidases and proteinases, Bacteroides fragilis is a valuable source of endo-beta-galactosidase for the structural analysis of carbohydrate chains.
D001441:Bacteroides fragilis / Q000201:enzymology*; D002413:Cations, Divalent / Q000494:pharmacology; D002850:Chromatography, Gel; D004925:Escherichia / Q000201:enzymology; D005696:Galactosidases / Q000378:metabolism*; D006026:Glycoside Hydrolases; D006863:Hydrogen-Ion Concentration; D009844:Oligosaccharides / Q000494:pharmacology; D013379:Substrate Specificity; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013696:Temperature; D001616:beta-Galactosidase / Q000302:isolation & purification / Q000378:metabolism*
D002413:Cations, Divalent; D009844:Oligosaccharides; D013439:Sulfhydryl Reagents; D005696:Galactosidases; D006026:Glycoside Hydrolases; C026093:keratan-sulfate endo-1,4-beta-galactosidase; D001616:beta-Galactosidase