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Hyperthermophilic redox chemistry: a re-evaluation
P L Hagedoorn1, M C Driessen, M van den Bosch
1Wageningen University and Research Centre, Department of Biomolecular Sciences, The Netherlands. peter.leonhagedoorn@epr.bc.wau.nl
FEBS Letters
|January 1, 1999
Summary
The redox chemistry of Pyrococcus furiosus rubredoxin and ferredoxin shows normal temperature dependence. Direct voltammetry is reliable for determining redox potential temperature effects, unlike EPR monitoring.
Area of Science:
- Biochemistry
- Electrochemistry
- Protein Science
Background:
- Pyrococcus furiosus rubredoxin and ferredoxin are iron-sulfur proteins involved in electron transfer.
- Understanding their redox properties is crucial for bioenergetics and enzyme mechanisms.
Purpose of the Study:
- To investigate the temperature dependence of redox potentials (Em) for P. furiosus rubredoxin and ferredoxin.
- To compare the reliability of direct voltammetry and Electron Paramagnetic Resonance (EPR) monitored titrations for these measurements.
Main Methods:
- Direct voltammetry was used to measure the redox potentials of the proteins at varying temperatures.
- EPR monitored bulk titrations were performed to assess redox potential changes with temperature.
Main Results:
- Direct voltammetry revealed a linear, normal temperature dependence for the Em of both rubredoxin and ferredoxin.
- The measured Em values showed no significant pH dependence within the studied range.
- EPR monitoring was found to be unreliable for determining temperature dependence due to protein conformational changes upon rapid freezing.
Conclusions:
- Direct voltammetry provides accurateEm temperature dependence data for these iron-sulfur proteins.
- EPR monitoring can be misleading for temperature-dependent redox studies of proteins that undergo conformational changes upon freezing.