title: Purification and biochemical properties of multiple xylanases from Aspergillus ochraceus tolerant to Hg2+ ion and a wide range of pH.
abstract: Production of multiple xylanases, in which each enzyme has a specific characteristic, can be one strategy to achieve the effective hydrolysis of xylan. Three xylanases (xyl 1, xyl 2, and xyl 3) from Aspergillus ochraceus were purified by chromatography using diethylaminoethyl (DEAE) cellulose, Biogel P-60, and Sephadex G-100 columns. These enzymes are glycoproteins of low molecular weight with an optimum temperature at 60 °C. The glycosylation presented is apparently not related to thermostability, since xyl 3 (20 % carbohydrate) was more thermostable than xyl 2 (67 % carbohydrate). Xyl 3 was able to retain most of its activity in a wide range of pH (3.5-8.0), while xyl 1 and xyl 2 presented optimum pH of 6.0. Xyl 1 and xyl 2 were activated by 5 and 10 mM MnCl2 and CoCl2, while xyl 3 was activated by 1 mM of the same compounds. Interestingly, xyl 2 presented high tolerance toward mercury ion. Xylanases from A. ochraceus hydrolyzed xylans of different origins, such as birchwood, oat spelt, larchwood, and eucalyptus (around 90 % or more), except xyl 2 and xyl 3 that hydrolyzed with lesser efficiency eucalyptus (66.7 %) and oat spelt (44.8 %) xylans.
authors: Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, Ribeirão Preto, SP, 14040-901, Brazil.
authors: Michele
authors: M
authors: Michelin
authors: Tony M
authors: TM
authors: Silva
authors: João A
authors: JA
authors: Jorge
authors: Maria de Lourdes T M
authors: Mde L
authors: Polizeli
mesh_terms: D001235:Aspergillus ochraceus / Q000201:enzymology*; D025141:Drug Resistance, Fungal; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000302:isolation & purification; D005656:Fungal Proteins / Q000737:chemistry / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D008628:Mercury; D013379:Substrate Specificity
chemical_list: D005656:Fungal Proteins; D043364:Endo-1,4-beta Xylanases; D008628:Mercury