title: Purification and characterization of a thermostable hypothetical xylanase from Aspergillus oryzae HML366.
abstract: In the current study, fermentation broth of Aspergillus oryzae HML366 in sugar cane bagasse was subjected to ultrafiltration and ion exchange chromatography, and two xylanases, XynH1 and XynH2, were purified. Time-of-flight mass spectrometry coupled with SDS-PAGE analysis revealed that XynH1 is identical to the hypothetical A. oryzae RIB40 protein XP_001826985.1, with a molecular weight of 33.671 kDa. Likewise, XynH2 was identified as xylanase XynF1 with a molecular weight of 35.402 kDa. Sequence analysis indicated that XynH1 belongs to glycosyl hydrolases family 10. The specific activity of XynH1 was measured at 476.9 U/mg. Optimal xylanase activity was observed at pH 6.0, and enzyme remained active within pH 4.0-10.0 and at a temperature below 70 °C. Mg(2+), Mn(2+), Ca(2+), and K(+) enhanced the XynH1 xylanase activity to 146, 122, 114, and 108%, respectively. XynH1 hydrolyzed Birchwood xylan and Larchwood xylan effectively. The K m and V max of XynH1 values determined were 1.16 mM and 336 μmol/min/mg with Birchwood xylan as the substrate. A. oryzae HML366 xylanase XynH1 showed superior heat and pH tolerance, therefore may have significant applications in paper and biofuel industries. These studies constitute the first investigation of the xylanase activities of the hypothetical protein XP_001826985.1 form A. oryzae.
authors.affiliation: College of Chemical and Biological Engineering, Hechi University, Yizhou, Guangxi, 546300, China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: He
authors.forename: Yongling
authors.initials: Y
authors.lastname: Qin
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.forename: Guiguang
authors.initials: G
authors.lastname: Chen
authors.forename: Zhiqun
authors.initials: Z
authors.lastname: Liang
mesh_terms: D000595:Amino Acid Sequence; D001236:Aspergillus oryzae / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D006358:Hot Temperature; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010802:Phylogeny; D031786:Saccharum / Q000378:metabolism / Q000382:microbiology; D016415:Sequence Alignment; D012988:Soil Microbiology; D013379:Substrate Specificity
chemical_list: D005656:Fungal Proteins; D043364:Endo-1,4-beta Xylanases