Publicação: Purification and characterization of two β-glucosidases from the thermophilic fungus Thermoascus aurantiacus
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β-Glucosidase from the fungus Thermoascus aurantiacus grown on semi-solid fermentation medium (using ground corncob as substrate) was partially purified in 5 steps-ultrafiltration, ethanol precipitation, gel filtration and 2 anion exchange chromatography runs, and characterized. After the first anion exchange chromatography, β-glucosidase activity was eluted in 3 peaks (Gl-1, Gl-2, Gl-3). Only the Gl-2 and Gl-3 fractions were adsorbed on the gel matrix. Gl-2 and Gl-3 exhibited optimum pH at 4.5 and 4.0, respectively. The temperature optimum of both glucosidases was at 75-80°C. The pH stability of Gl-2 (4.0-9.0) was higher than Gl-3 (5.5-8.5); both enzyme activities showed similar patterns of thermostability. Under conditions of denaturing gel chromatography the molar mass of Gl-2 and Gl-3 was 175 and 157 kDa, respectively. Using 4-nitrophenyl β-D-glucopyranoside as substrate, Km values of 1.17 ± 0.35 and 1.38 ± 0.86 mmol/L were determined for Gl-2 and Gl-3, respectively. Both enzymes were inhibited by Ag+ and stimulated by Ca2+.
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beta glucosidase, calcium, silver, Ascomycetes, Brazil, chemistry, drug antagonism, enzymology, gel chromatography, ion exchange chromatography, isolation and purification, kinetics, metabolism, molecular weight, pH, polyacrylamide gel electrophoresis, precipitation, ultrafiltration, Ascomycota, beta-Glucosidase, Calcium, Chromatography, Gel, Chromatography, Ion Exchange, Electrophoresis, Polyacrylamide Gel, Hydrogen-Ion Concentration, Kinetics, Molecular Weight, Precipitation, Silver, Ultrafiltration
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Folia Microbiologica, v. 47, n. 6, p. 685-690, 2002.
