title: A novel pH-stable, bifunctional xylanase isolated from a deep-sea microorganism, Demequina sp. JK4.
abstract: A genomic library was constructed to clone a xylanase gene (Mxyn10) from Demequina sp. JK4 isolated from a deep sea. Mxyn10 encoded a 471 residue protein with a calculated molecular mass of 49 kDa. This protein showed the highest sequence identity (70%) with the xylanase from Streptomyces lividans. Mxyn10 contains a catalytic domain that belongs to the glycoside hydrolase family 10 (GH10) and a carbohydrate-binding module (CBM) belonging to family 2. The optimum pH and temperature for enzymatic activity were pH 5.5 and 55 degrees C, respectively. Mxyn10 exhibited good pH stability, remaining stable after treatment with buffers ranging from pH 3.5 to 10.0. The protein was not significantly affected by a variety of chemical reagents, including some compounds that usually inhibit the activity of other related enzymes. In addition, Mxyn10 showed activity on cellulose. These properties mark Mxyn10 as a potential enzyme for industrial application and saccharification processes essential for bioethanol production.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. of China.
authors.forename: Xin
authors.initials: X
authors.lastname: Meng
authors.forename: Zongze
authors.initials: Z
authors.lastname: Shao
authors.forename: Yuzhi
authors.initials: Y
authors.lastname: Hong
authors.forename: Ling
authors.initials: L
authors.lastname: Lin
authors.forename: Chanjuan
authors.initials: C
authors.lastname: Li
authors.forename: Ziduo
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000192:Actinomycetales / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012623:Seawater / Q000382:microbiology*; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D002482:Cellulose; D043364:Endo-1,4-beta Xylanases