| Full text | |
| Author(s): |
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]
Total Authors: 7
|
| Affiliation: | [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
Total Affiliations: 3
|
| Document type: | Journal article |
| Source: | WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY; v. 28, n. 11, p. 3179-3186, NOV 2012. |
| Web of Science Citations: | 10 |
| Abstract | |
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) | |