Six strains of Bacteroides fragilis were examined and all found to produce endo-beta-galactosidase, an enzyme that hydrolyses internal β-galactosidic linkages of oligosaccharides belonging to the poly-N-acetyl-lactosamine series, with the common structure GlcNAc β 1 leads to 3Gal β 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 β 1 leads to 4GlcNAc β 1 leads to 3Gal β 1 leads to 4Glc, at about twice the rate of the type 1 isomer, Gal β 1 leads to 3GlcNAc β 1 leads to 3Gal β 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.
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Research Article| August 01 1983
Isolation and characterization of an endo-β-galactosidase from Bacteroides fragilis
Biochem J (1983) 213 (2): 485–494.
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P Scudder, K Uemura, J Dolby, M N Fukuda, T Feizi; Isolation and characterization of an endo-β-galactosidase from Bacteroides fragilis. Biochem J 1 August 1983; 213 (2): 485–494. doi: https://doi.org/10.1042/bj2130485
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