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Inter- and intra-molecular electron transfer in the cytochrome bc(1) complex
Chang-An Yu1, Xiaolin Wen, Kunhong Xiao
1Department of Biochemistry and Molecular Biology, NRC-255, OAES, Oklahoma State University, Stillwater, OK74078, USA. cayuq@okstate.edu
Biochimica Et Biophysica Acta
|September 11, 2002
Summary
This review compares electron transfer rates in the cytochrome bc1 complex, identifying the iron-sulfur protein
Area of Science:
- Biochemistry
- Bioenergetics
- Molecular Biology
Background:
- The cytochrome bc1 complex is crucial for cellular energy conservation.
- Understanding its electron transfer mechanisms is key to elucidating bioenergetic pathways.
Purpose of the Study:
- To compare intra-molecular and inter-molecular electron transfer rate constants in the high-potential branch of the cytochrome bc1 complex.
- To elucidate the reaction mechanism of this vital energy-conserving complex.
Main Methods:
- Conventional stopped-flow spectroscopy.
- pH-induced electron transfer.
- Photoactivated ruthenium complex-induced electron transfer.
- Photoreleaseable caged quinol.
Main Results:
- Identified electron transfer rate constants for various redox centers.
- Determined that steps with rate constants significantly exceeding the turnover number (800 s-1) are not rate-limiting.
Conclusions:
- The rate-limiting step is likely the movement of the iron-sulfur protein head domain, governed by the cytochrome b redox state.
- This movement occurs between the electron-accepting (b-state) and electron-donating (c1-state) positions.