Purification and biochemical characterization of β-xylosidase from Humicola grisea var. thermoidea |
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Authors: | Elzira Maria de Almeida Maria de Lourdes TM Polizeli Héctor Francisco Terenzi João Atilio Jorge |
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Institution: | Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paula, 14040-901 Ribeirão . Preta, São Paulo, Brazil |
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Abstract: | Abstract β-d-Xylosidase production was maximal for Humicola grisea var. thermoidea grown on xylan as the sole carbon source. The main β-d-xylosidase activity was localised in the periplasm. β-Xylosidase was purified from crude extracts by heat treatment, ammonium sulfate precipitation and chromatography on DEAE-cellulose and Sephadex G-100. The purified enzyme was a monomer of molecular mass estimated to be 43 kDa by SDS-PAGE and gel filtration. Optima of pH and temperature were 6.0 and 50 °C, respectively. The enzyme activity was stimulated by Ca2+, Fe2+, and Mg2+. The purified β-xylosidase did not exhibit xylanase, carboxymethylcelullase, galactosidase, glucosidase, fucosidase or arabinosidase activities. The purified β-xylosidase hydrolysed xylobiose and xylo-oligosaccharides of up to five monosaccharide units. The enzyme had a K m of 0.49 mM for p -nitrophenyl- β -d-xylopyranoside and was not inhibited by its product, xylose. |
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Keywords: | Humicola grisea β-d-Xylosidase Xylan-degrading enzyme Thermophilic fungi |
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