Enzymes responsible for the metabolism of saikosaponins from Eubacterium sp. A-44, a human intestinal anaerobe.
From a human intestinal bacterium, Eubacterium sp. A-44, which is capable of hydrolyzing saikosaponins to saikogenins, two glycosidases, beta-D-glucosidase and a novel type of beta-D-fucosidase, were isolated and characterized as saikosaponin-hydrolyzing beta-D-glucosidase and prosaikogenin-hydrolyzing beta-D-fucosidase. Relative to the hydrolyzing activities toward saikosaponins a, b1 and b2, the beta-D-glucosidase showed lower ability to hydrolyze saikosaponin d, but no ability to hydrolyze saikosaponin c or prosaikogenins. By Sephacryl S-300 column chromatography, the molecular weight of prosaikogenin-hydrolyzing beta-D-fucosidase was estimated to be about 130 kDa. The beta-D-fucosidase could hydrolyze prosaikogenins A and F, but not prosaikogenins D and G or saikosaponins. Relative to p-nitrophenyl beta-D-fucoside-hydrolyzing activity, this enzyme had 32.0% and 22.2% of its hydrolyzing ability toward p-nitrophenyl beta-D-glucoside and p-nitrophenyl beta-D-galactoside, respectively. p-Nitrophenyl beta-D-fucoside-hydrolyzing activity was inhibited by D-fucose, and was weakly inhibited by D-glucose, D-glucono delta-lactone, D-galactose and D-galactono delta-lactone. By combining these two glycosidases, saikosaponins a and b1 were converted to their saikogenins via the corresponding prosaikogenins.
Kida
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Department of Cell-Resources Engineering, Research Institute for Wakan-Yaku (Traditional Sino-Japanese Medicines), Sugitani, Toyama, Japan.
Akao
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Meselhy
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Hattori
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D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism*; D003470:Culture Media; D005051:Eubacterium / Q000378:metabolism*; D005243:Feces / Q000382:microbiology; D005959:Glucosidases / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007422:Intestines / Q000201:enzymology*; D008970:Molecular Weight; D009828:Oleanolic Acid / Q000031:analogs & derivatives*; D012502:Sapogenins / Q000378:metabolism*; D012503:Saponins; D013379:Substrate Specificity; D005644:alpha-L-Fucosidase / Q000302:isolation & purification / Q000378:metabolism
D000894:Anti-Inflammatory Agents, Non-Steroidal; D003470:Culture Media; D012502:Sapogenins; D012503:Saponins; D009828:Oleanolic Acid; D005959:Glucosidases; D005644:alpha-L-Fucosidase; C025759:saikosaponin D