title: Overproduction and characterization of seleno-methionine xylanase T-6.
abstract: The extracellular xylanase from Bacillus stearothermophilus T-6 is a thermostable alkaline tolerant enzyme that was found to bleach pulp optimally at pH 9 and 65 degrees C, and was successfully used in a large-scale bio-bleaching mill trial. In an attempt to obtain a heavy atom derivative suitable for complete X-ray analysis, xylanase T-6 was labeled biosynthetically with seleno-methionine, resulting in a 'built-in' array of atoms with specific X-ray anomalous scattering signal. Optimization of growth conditions resulted in over 0.8 g of homogeneous seleno-methionine xylanase T-6 per liter culture. The seleno-methionine enzyme was shown to be fully active and produced single crystals suitable for complete multiple wavelength anomalous diffraction (MAD) structural analysis.
authors.affiliation: Department of Food Engineering and Biotechnology, Technion, Haifa, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Mechaly
authors.forename: A
authors.initials: A
authors.lastname: Teplitsky
authors.forename: V
authors.initials: V
authors.lastname: Belakhov
authors.forename: T
authors.initials: T
authors.lastname: Baasov
authors.forename: G
authors.initials: G
authors.lastname: Shoham
authors.forename: Y
authors.initials: Y
authors.lastname: Shoham
mesh_terms: D001709:Biotechnology / Q000379:methods; D018360:Crystallography, X-Ray; D004926:Escherichia coli; D001411:Geobacillus stearothermophilus / Q000201:enzymology*; D010209:Paper; D012645:Selenomethionine / Q000378:metabolism*; D013329:Structure-Activity Relationship; D043325:Xylan Endo-1,3-beta-Xylosidase; D014995:Xylosidases / Q000096:biosynthesis* / Q000737:chemistry*
chemical_list: D012645:Selenomethionine; D014995:Xylosidases; D043325:Xylan Endo-1,3-beta-Xylosidase