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Redox-coupled dynamics and folding in cytochrome c.
Laura B Sagle1, Jörg Zimmermann, Shigeo Matsuda
1Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Journal of the American Chemical Society
|June 15, 2006
Summary
This study investigated cytochrome c flexibility and protein unfolding using IR spectroscopy. Results indicate oxidized cytochrome c is not more flexible but exhibits increased local unfolding, potentially regulating electron transfer.
Area of Science:
- Biochemistry
- Biophysics
- Molecular Biology
Background:
- Cytochrome c is a key mitochondrial electron carrier, crucial for cellular respiration.
- Its redox properties and protein folding have been extensively studied.
- Previous research suggested increased flexibility in oxidized cytochrome c, hypothesizing evolved dynamics control redox properties.
Purpose of the Study:
- To test the hypothesis that protein dynamics control cytochrome c's redox properties.
- To investigate the relationship between cytochrome c's redox state and its flexibility/unfolding.
- To explore the role of local unfolding in regulating electron transfer.
Main Methods:
- Incorporation of carbon-deuterium bonds throughout cytochrome c.
- Characterization of absorption frequencies and line widths using infrared (IR) spectroscopy.
- Analysis of redox-dependent changes in protein structure and dynamics.
Main Results:
- IR spectra revealed redox-dependent changes in absorption frequencies for proximal heme residues.
- No significant changes in line widths were observed, indicating no difference in flexibility between oxidized and reduced states.
- Spectra demonstrated a significant equilibrium between folded and locally unfolded protein, increasing with oxidation.
Conclusions:
- Cytochrome c's flexibility does not differ between oxidized and reduced states.
- Oxidized cytochrome c exhibits increased local unfolding compared to the reduced state.
- Local unfolding may represent an evolved mechanism for controlling electron transfer in cytochrome c.
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