Mechanism of the inhibition of milk xanthine oxidase activity by metal ions: a transient kinetic study
| Autor: | Apurba Kumar Sau, Samaresh Mitra, Madhu Sudan Mondal |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
chemistry.chemical_classification
Xanthine Oxidase Half-reaction Metal ions in aqueous solution Kinetics Inorganic chemistry Biophysics Oxidative phosphorylation Biochemistry Ion chemistry.chemical_compound Milk chemistry Metals Structural Biology Oxidoreductase Animals Cattle Steady state (chemistry) Xanthine oxidase Molecular Biology |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology. 1480:302-310 |
| ISSN: | 0167-4838 |
| Popis: | The nature and mechanism of the inhibition of the oxidoreductase activity of milk xanthine oxidase (XO) by Cu(2+), Hg(2+) and Ag(+) ions has been studied by steady state and stopped flow transient kinetic measurements. The results show that the nature of the inhibition is noncompetitive. The inhibition constants for Cu(2+) and Hg(2+) are in the micromolar and that for Ag(+) is in the nanomolar range. This suggests that the metal ions have strong affinity towards XO. pH dependence studies of the inhibition indicate that at least two ionisable groups of XO are involved in the binding of these metal ions. The effect of the interaction of the metal ions on the reductive and oxidative half reactions of XO has been investigated, and it is observed that the kinetic parameters of the reductive half reaction are not affected by these metal ions. However, the interaction of these metal ions with XO significantly affects the kinetic parameters of the oxidative half reaction. It is suggested that this may be the main cause for the inhibition of XO activity by the metal ions. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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