title: Hydrolysis of isoflavone glycosides by a thermostable β-glucosidase from Pyrococcus furiosus.
abstract: The recombinant β-glucosidase from the hyperthermophilic archaeon  Pyrococcus furiosus  was purified with a specific activity of 330 U/mg for genistin by His-trap chromatography. The specific activity of the purified enzyme followed the order genistin > daidzin > glycitin> malonyl glycitin > malonyl daidzin > malonyl genistin. The hydrolytic activity for genistin was highest at pH 6.0 and 95 °C with a half-life of 59 h, a K(m) of 0.5 mM, and a k(cat) of 6050 1/s. The enzyme completely hydrolyzed 1.0 mM genistin, daidzin, and glycitin within 100, 140, and 180 min, respectively. The soybean flour extract at 7.5% (w/v) contained 1.0 mM genistin, 0.9 mM daidzin, and 0.3 mM glycitin. Genistin, daidzin, and glycitin in the soybean flour extract were completely hydrolyzed after 60, 75, and 120 min, respectively. Of the reported β-glucosidases, P. furiosusβ-glucosidase exhibited the highest thermostability, k(cat), k(cat)/K(m), yield, and productivity for hydrolyzing genistin. These results suggest that this enzyme may be useful for the industrial hydrolysis of isoflavone glycosides.
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, Republic of Korea.
authors.forename: Soo-Jin
authors.initials: SJ
authors.lastname: Yeom
authors.forename: Bi-Na
authors.initials: BN
authors.lastname: Kim
authors.forename: Yeong-Su
authors.initials: YS
authors.lastname: Kim
authors.forename: Deok-Kun
authors.initials: DK
authors.lastname: Oh
mesh_terms: D004795:Enzyme Stability; D006027:Glycosides / Q000378:metabolism*; D006358:Hot Temperature; D006868:Hydrolysis; D007529:Isoflavones / Q000378:metabolism*; D007700:Kinetics; D020027:Pyrococcus furiosus / Q000201:enzymology*; D011994:Recombinant Proteins; D013025:Glycine max / Q000737:chemistry; D013379:Substrate Specificity; D001617:beta-Glucosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D006027:Glycosides; D007529:Isoflavones; D011994:Recombinant Proteins; C040641:genistin; C013908:daidzin; D001617:beta-Glucosidase; C433283:glycitin