The stability of extracellular beta-glucosidase from Aspergillus niger is significantly enhanced by non-covalently attached polysaccharides
Jazyk angličtina Země Spojené státy americké Médium print
Typ dokumentu časopisecké články, Research Support, U.S. Gov't, Non-P.H.S.
PubMed
9131791
DOI
10.1007/bf02814712
Knihovny.cz E-zdroje
- MeSH
- Aspergillus niger enzymologie MeSH
- beta-glukosidasa chemie izolace a purifikace metabolismus MeSH
- kinetika MeSH
- makromolekulární látky MeSH
- polysacharidy chemie izolace a purifikace MeSH
- stabilita enzymů MeSH
- Publikační typ
- časopisecké články MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Názvy látek
- beta-glukosidasa MeSH
- makromolekulární látky MeSH
- polysacharidy MeSH
The removal of noncovalently bound polysaccharide coating from the extracellular enzymes of Aspergillus niger, by the technique of compartmental electrophoresis, had a very dramatic effect on the stability of beta-glucosidase. The polysaccharide-beta-glucosidase complex was extremely resistant to proteinases and far more stable against urea and temperature as compared with polysaccharide-free beta-glucosidase. The beta-glucosidase-polysaccharide complex was 18-, 36-, 40- and 82-fold more stable against chymotrypsin, 3 mol/L urea, total thermal denaturation and irreversible thermal denaturation, respectively, as compared with polysaccharide-free beta-glucosidase. The activation energy of polysaccharide-complexed beta-glucosidase (55 kJ/mol) was lower than polysaccharide-free enzyme (61 kJ/mol), indicating a slight activation of the enzyme by the polysaccharide. No significant difference could be detected in the specificity constant (V/K(m)) for A-nitrophenyl beta-D-glucopyranoside between polysaccharide-free and polysaccharide-complexed beta-glucosidase. We suggest that the function of these polysaccharides secreted by fungi including A. niger might be to protect the extracellular enzymes from proteolytic degradation, hence increasing their life span.
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Purification and characterization of a beta-glucosidase from Aspergillus niger
