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Redox-triggered events in cytochrome c nitrite reductase
James D Gwyer1, Hayley C Angove, David J Richardson
1Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, UK.
Bioelectrochemistry (Amsterdam, Netherlands)
|April 28, 2004
Summary
Protein film voltammetry revealed how heme oxidation state profoundly impacts Escherichia coli nitrite reductase activity. Enzyme reactivity with substrates like nitrite and inhibitors like cyanide is redox-dependent.
Area of Science:
- Biochemistry
- Enzymology
- Bioelectrochemistry
Background:
- Escherichia coli cytochrome c nitrite reductase is a homodimeric enzyme with 10 heme centers.
- These centers exhibit a range of reduction potentials, influencing enzyme function.
Purpose of the Study:
- To investigate the influence of heme oxidation state on the reactivity of Escherichia coli cytochrome c nitrite reductase.
- To characterize redox-triggered events in this multi-centered enzyme using protein film voltammetry.
Main Methods:
- Protein film voltammetry (PFV) was employed to control and monitor enzyme activity.
- The enzyme sample was precisely controlled by an electrode at all times, allowing high-resolution activity description across the electrochemical potential domain.
Main Results:
- Heme oxidation state significantly affects enzyme interactions with substrates (nitrite, hydroxylamine) and inhibitors (cyanide).
- Current-potential profiles demonstrated distinct reactivity patterns dependent on the heme redox state.
Conclusions:
- Protein film voltammetry is a powerful technique for studying redox-triggered events in complex enzymes.
- Understanding heme redox-dependent reactivity is crucial for elucidating the enzyme's catalytic mechanism.