Reaction of the Desulfoferrodoxin from Desulfoarculus baarsii with Superoxide Anion
| Autor: | Vincent Nivière, Marc Fontecave, Danièle Touati, Murielle Lombard |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Antioxidant
medicine.medical_treatment Oxidative phosphorylation 010402 general chemistry medicine.disease_cause 01 natural sciences Biochemistry Superoxide dismutase 03 medical and health sciences chemistry.chemical_compound medicine Molecular Biology Escherichia coli 030304 developmental biology chemistry.chemical_classification 0303 health sciences biology Chemistry Superoxide Cell Biology Superoxide reductase activity 0104 chemical sciences Enzyme Superoxide reductase biology.protein |
| Zdroj: | Journal of Biological Chemistry. 275:115-121 |
| ISSN: | 0021-9258 |
| Popis: | Desulfoferrodoxin is a small protein found in sulfate-reducing bacteria that contains two independent mononuclear iron centers, one ferric and one ferrous. Expression of desulfoferrodoxin from Desulfoarculus baarsii has been reported to functionally complement a superoxide dismutase deficient Escherichia coli strain. To elucidate by which mechanism desulfoferrodoxin could substitute for superoxide dismutase in E. coli, we have purified the recombinant protein and studied its reactivity toward O-(2). Desulfoferrodoxin exhibited only a weak superoxide dismutase activity (20 units mg(-1)) that could hardly account for its antioxidant properties. UV-visible and electron paramagnetic resonance spectroscopy studies revealed that the ferrous center of desulfoferrodoxin could specifically and efficiently reduce O-(2), with a rate constant of 6-7 x 10(8) M(-1) s(-1). In addition, we showed that membrane and cytoplasmic E. coli protein extracts, using NADH and NADPH as electron donors, could reduce the O-(2) oxidized form of desulfoferrodoxin. Taken together, these results strongly suggest that desulfoferrodoxin behaves as a superoxide reductase enzyme and thus provide new insights into the biological mechanisms designed for protection from oxidative stresses. |
| Databáze: | OpenAIRE |
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