Purification and characterization of two beta-glucosidases from the thermophilic fungus Thermoascus aurantiacus
Language English Country United States Media print
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
12630320
DOI
10.1007/bf02818672
Knihovny.cz E-resources
- MeSH
- Ascomycota enzymology MeSH
- beta-Glucosidase antagonists & inhibitors chemistry isolation & purification metabolism MeSH
- Chemical Precipitation MeSH
- Chromatography, Ion Exchange MeSH
- Electrophoresis, Polyacrylamide Gel MeSH
- Chromatography, Gel MeSH
- Kinetics MeSH
- Hydrogen-Ion Concentration MeSH
- Molecular Weight MeSH
- Silver pharmacology MeSH
- Ultrafiltration MeSH
- Calcium pharmacology MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Brazil MeSH
- Names of Substances
- beta-Glucosidase MeSH
- Silver MeSH
- Calcium MeSH
beta-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, beta-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 degrees 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 beta-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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