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  • 1
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Bifidobacterium adolescentis was grown anaerobically in medium enriched with α-D-galactosides. α-Galactosidase (EC 3.2.1.22) was released from the cells by ultrasonic treatment and purified 36-fold by ultrafiltration, ammonium-sulphate precipitation, anion-exchange chromatography, and size-exclusion chromatography. Two protein bands were consistantly observed after sodium-dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). Electrophoretically homogeneous α-galactosidase was only obtained by electroelution. The enzyme had an apparent molecular mass of 344 kDa and 79 kDa as judged by size-exclusion chromatography and SDS-PAGE, respectively. Activity-staining after nondenaturing SDS-PAGE indicated an apparent molecular mass of 145 kDa. Thus, a tetrameric structure of the protein is suggested. The α-galactosidase showed optimal activity at pH 5.5 and 55°C. Lower pH values and higher temperatures rapidly inactivated α-galactosidase. The enzyme hydrolyzed specifically α-galactosidic linkages, and α-(1-3)-linkages were hydrolyzed at a higher rate compared to α-(1-6)-linkages. Hydrolysis of galactosides followed normal saturation kinetics; KM-values for p-nitrophenyl-α-galactopyranoside (p-NPG) and raffinose were calculated with 0.957 mM and 4.12 mM, respectively.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Low-molecular-mass β-(2,6)-linked fructose-oligosaccharides (β-(2,6)-FOS) were examined as a new carbohydrate source for growth of bifidobacteria. β-(2,6)-FOS were prepared from microbial high-molecular-mass levan by acid hydrolysis and refined by cation-exchange chromatography. 13C-NMR spectroscopy confirmed the presence of predominantly β-(2,6)-fructosyl linkages in the oligosaccharides. More than 80%β-(2,6)-FOS was recovered after in vitro incubation with amylolytic and proteolytic enzymes, implying resistance to degradation in the upper intestinal tract. Bifidobacterium adolescentis, B. longum, B. breve, and B. pseudocatenulatum were studied in vitro for their ability to metabolize β-(2,6)-FOS. Growth, decrease in pH, formation of short- chain fatty acids (lactate, acetate, formate) and degradation of β-(2,6)-FOS were markedly different among species. B. adolescentis showed the best growth, produced the highest amounts of organic acids and metabolized both short- and long-chain β-(2,6)-FOS.
    Type of Medium: Electronic Resource
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