Kinetic Study of the Activation Process of beta-Galactosidase from Escherichia coli by Mg2+
| Autor: | Jeannine M. Yon, Odile M. Viratelle, Jean-Pierre Tenu |
|---|---|
| Rok vydání: | 1972 |
| Předmět: |
inorganic chemicals
chemistry.chemical_classification Conformational change Protein Conformation Stereochemistry Kinetics Substrate (chemistry) medicine.disease_cause Biochemistry Galactoside Galactosidases Catalysis Ion Enzyme Activation chemistry.chemical_compound Enzyme chemistry Escherichia coli Biophysics medicine Magnesium Edetic Acid Protein Binding |
| Zdroj: | European Journal of Biochemistry. 26:112-118 |
| ISSN: | 1432-1033 0014-2956 |
| DOI: | 10.1111/j.1432-1033.1972.tb01746.x |
| Popis: | The action of Mg2+ ions on β-galactosidase activity has been studied under strictly controlled conditions with different substrates. The activation effect does not depend on the substrate. In the absence of Mg2+ ions, a residual activity has been found and the catalytic properties of Mg2+-free enzyme have been determined. The activation process induced by Mg2+ is a slow process, the rate of which depends on the Mg2+ concentration. The deactivation process obtained by adding EDTA is also a slow process. Activation by Mg2+ is not a cooperative process. The apparent dissociation constant of the Mg2+ enzyme complexe is rather small, 0.65 ± 0.05 μM. The kinetics of activation and deactivation have been studied with phenyl galactoside as substrate. The results indicate that activation by Mg2+ operates through a binding with free enzyme. This binding involves at least two steps: the first and more rapid one is a single metal-protein binding, the following slow step probably involves a conformational change of the enzyme induced by the metal binding. |
| Databáze: | OpenAIRE |
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