title: Purification and properties of a psychrotrophic Trichoderma sp. xylanase and its gene sequence.
abstract: A psychrotrophic fungus identified as Trichoderma sp. SC9 produced 36.7 U/ml of xylanase when grown on a medium containing corncob xylan at 20 °C for 6 days. The xylanase was purified 37-fold with a recovery yield of 8.2%. The purified xylanase appeared as a single protein band on SDS-PAGE with a molecular mass of approximately 20.5 kDa. The enzyme had an optimal pH of 6.0, and was stable over pH 3.5-9.0. The optimal temperature of the xylanase was 42.5 °C and it was stable up to 35 °C at pH 6.0 for 30 min. The xylanase was thermolabile with a half-life of 23.9 min at 45 °C. The apparent K(m) values of the xylanase for birchwood, beechwood, and oat-spelt xylans were found to be 3, 2.1, and 16 mg/ml respectively. The xylanase hydrolyzed beechwood xylan and birchwood xylan to yield mainly xylobiose as end products. The enzyme-hydrolysed xylotriose, xylotetraose, and xylopentose to produce xylobiose, but it hardly hydrolysed xylobiose. A xylanase gene (xynA) with an open reading frame of 669 nucleotide base pairs (bp), encoding 222 amino acids, from the strain was cloned and sequenced. The deduced amino acid sequence of XynA showed 85% homology with Xyn2 from a mesophilic strain of Trichoderma viride.
authors.affiliation: Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, People's Republic of China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhou
authors.forename: Huifang
authors.initials: H
authors.lastname: Zhu
authors.forename: Qiaojuan
authors.initials: Q
authors.lastname: Yan
authors.forename: Priti
authors.initials: P
authors.lastname: Katrolia
authors.forename: Zhengqiang
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; 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; D008969:Molecular Sequence Data; D012988:Soil Microbiology; D013379:Substrate Specificity; D014242:Trichoderma / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D005656:Fungal Proteins; D043364:Endo-1,4-beta Xylanases