Extracellular β-D-glucosidase from Chaetomium thermophilum var. coprophilum: production, purification and some biochemical properties
✍ Scribed by Leandra Lórice Venturi; Maria de Lourdes Polizeli; Héctor Francisco Terenzi; Rosa dos Prazeres Melo Furriel; João Atílio Jorge
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 202 KB
- Volume
- 42
- Category
- Article
- ISSN
- 0233-111X
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✦ Synopsis
The thermophilic fungus Chaetomium thermophilum var. coprophilum produced large amounts of extracellular and intracellular β-glucosidase activity when grown on cellulose or cellobiose as carbon sources. The presence of glucose in the culture medium drastically decreased the level of β-glucosidase activity, while cycloheximide prevented the induction of the extracellular enzyme activity by cellobiose. An extracellular β-glucosidase induced by avicel was purified by a procedure involving acetone precipitation and chromatography on two DEAE-cellulose columns. The purified enzyme was a basic protein, with a carbohydrate content of 73%. The deglycosylated enzyme exhibited a molecular mass of 43 kDa, with pH and temperature optima of 5.5 and 65 °C respectively. The β-glucosidase hydrolysed only cellobiose and p-nitrophenyl-β-D-glucopyranoside, exhibiting apparent K m values of 3.13 mM and 0.76 mM, respectively. The native purified enzyme was stable up to 2 hours at 60 °C, and its thermal stability was directly dependent on glycosylation.