title: Characterization of a cold-active β-glucosidase from Paenibacillus xylanilyticus KJ-03 capable of hydrolyzing isoflavones daidzin and genistin.
abstract: Paenibacillus xylanilyticus KJ-03 isolated from konjac field, showed β-glucosidase activity on tryptic soy agar plate supplemented with 0.1 % esculin and 0.25 % ferric ammonium citrate. A genome library was constructed to obtain the β-glucosidase gene and a recombinant clone, pGlc2-3 was selected. The 2,247 bp gene encoding KJ-03 β-glucosidase consisted of 749 amino acids. The deduced amino acids of BglA were 61 % homologous with that of the β-glucosidase from Bacillus cereus AH1272, which belongs to the glycoside hydrolase family 3. His-tagged β-glucosidase was purified by using His-Trap column and characterized. KJ-03 β-glucosidase was showed as a single band with about 82 kDa on SDS-PAGE. The purified enzyme has optimal activity at 20 °C and pH 7.0 using p-NPβG and 72 % of the maximal activity was still remaining at 10 °C. The β-glucosidase has optimal activity at low temperatures indicating that it is a cold-active enzyme. The substrate specificity showed that the purified enzyme hydrolyzed aryl β-glucoside substrates and isoflavones such as daidzin and genistin.
authors.affiliation: Department of Biotechnology, College of Natural Resources and Life Science, Dong-A University, Busan, 604-714, South Korea.
authors.forename: Dong-Ju
authors.initials: DJ
authors.lastname: Park
authors.forename: Yong-Suk
authors.initials: YS
authors.lastname: Lee
authors.forename: Yong-Lark
authors.initials: YL
authors.lastname: Choi
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D007529:Isoflavones / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D056507:Paenibacillus / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D013379:Substrate Specificity; D001617:beta-Glucosidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D007529:Isoflavones; D011994:Recombinant Proteins; C040641:genistin; C013908:daidzin; D001617:beta-Glucosidase