title: Purification and characterization of an extracellular beta-xylosidase from the rumen anaerobic fungus Neocallimastix frontalis.
abstract: The purification of beta-xylosidase (beta-D-xyloside xylohydrolase, EC 3.2.1.37) from Neocallimastix frontalis was performed by ammonium sulphate precipitation, ion exchange chromatography, gel filtration and preparative isoelectric focusing. The enzyme had a molecular mass of 180,000 Da, an isoelectric point at pH 4.35 and catalysed the hydrolysis of p-nitrophenyl-beta-D-xylopyranoside optimally at pH 6.5 and 35 degrees C with a Km of 0.33 mg ml-1. The enzymatic activity was strongly increased by the presence of Ca2+, Mn2+, Zn2+, Co2+ or Mg2+ and completely inhibited by Hg2+ and p-chloromercuribenzoate. The purified protein also had a low level of xylanase activity.
authors: Laboratoire de Biologie Cellulaire Fongique, UMR CNRS 106, Université Lyon I, Villeurbanne, France.
authors: M
authors: M
authors: Hebraud
authors: M
authors: M
authors: Fevre
mesh_terms: D000818:Animals; D002852:Chromatography, Ion Exchange; D008411:Chytridiomycota / Q000201:enzymology*; D008970:Molecular Weight; D012417:Rumen / Q000382:microbiology; D012756:Sheep; D014995:Xylosidases / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D014995:Xylosidases; C026579:exo-1,4-beta-D-xylosidase