A novel xylan degrading beta-D-xylosidase: purification and biochemical characterization

Autor(es)

Michelin, Michele ^{[1, 2]} ; Peixoto-Nogueira, Simone C. ^[3] ; Silva, Tony M. ^[1] ; Jorge, Joao A. ^[1] ; Terenzi, Hector F. ^[1] ; Teixeira, Jose A. ^[2] ; Polizeli, Maria de Lourdes T. M. ^{[1, 3]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Biol, BR-14040901 Ribeirao Preto, SP - Brazil

^[2] Univ Minho, Dept Engn Biol, P-4710057 Braga - Portugal

^[3] Univ Sao Paulo, Fac Med Ribeirao Preto, Dept Bioquim & Imunol, BR-14040901 Ribeirao Preto, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY; v. 28, n. 11, p. 3179-3186, NOV 2012.
• Citações Web of Science: 10

Resumo

Aspergillus ochraceus, a thermotolerant fungus isolated in Brazil from decomposing materials, produced an extracellular beta-xylosidase that was purified using DEAE-cellulose ion exchange chromatography, Sephadex G-100 and Biogel P-60 gel filtration. beta-xylosidase is a glycoprotein (39 % carbohydrate content) and has a molecular mass of 137 kDa by SDS-PAGE, with optimal temperature and pH at 70 A degrees C and 3.0-5.5, respectively. beta-xylosidase was stable in acidic pH (3.0-6.0) and 70 A degrees C for 1 h. The enzyme was activated by 5 mM MnCl2 (28 %) and MgCl2 (20 %) salts. The beta-xylosidase produced by A. ochraceus preferentially hydrolyzed p-nitrophenyl-beta-d-xylopyranoside, exhibiting apparent K-m and V-max values of 0.66 mM and 39 U (mg protein)(-1) respectively, and to a lesser extent p-nitrophenyl-beta-d-glucopyranoside. The enzyme was able to hydrolyze xylan from different sources, suggesting a novel beta-d-xylosidase that degrades xylan. HPLC analysis revealed xylans of different compositions which allowed explaining the differences in specificity observed by beta-xylosidase. TLC confirmed the capacity of the enzyme in hydrolyzing xylan and larger xylo-oligosaccharides, as xylopentaose. (AU)

• Processo FAPESP: 10/52322-3 - Bioprospecção de fungos filamentosos produtores de holoenzimas com aplicação em biorefinaria
• Beneficiário: Maria de Lourdes Teixeira de Moraes Polizeli
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Regular