Electrochemical and Spectroscopic Investigations of the Cytochrome bc 1 Complex from Rhodobacter capsulatus
Abstract
The cytochrome bc1-complex from Rhodobacter capsulatus was investigated by protein electrochemistry and VIS/IR spectroscopy. Infrared difference spectra, which represent redoxinduced conformational changes of cofactors and their protein environment, show signals of the hemes, the quinone Q i , and small conformational changes of the protein backbone. Furthermore band features were tentatively assigned to protonated aspartic or glutamic acids involved in the redox transition of each of the b-hemes, a proline in that of the [2Fe2S] protein and an arginine in that of cytochrome bH. The midpoint potential of the [2Fe2S] protein was determined for the first time at physiological temperature to be +290 mV at pH 8.7. The reduced minus oxidized difference extinction coefficients of the α-bands of the cytochromes were calculated to 11.5 mM⁻¹ cm⁻¹, 19 mM⁻¹ cm⁻¹ and 6.7 mM⁻¹ cm⁻¹ for cytochrome c₁, bH, and bL respectively. A novel method has been developed to quantify protonation reactions of the complex during the redox reactions of its cofactors by evaluation of the buffer signals in the mid-infrared region. Values will be discussed in relation to the pHdependence of the midpoint potentials.
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BibTeX
@article{baymann2026electrochemical,
title = {{Electrochemical and Spectroscopic Investigations of the Cytochrome bc 1 Complex from Rhodobacter capsulatus}},
author = {Frauke Baymann and D. Robertson and P. Dutton and Werner Mäntele},
journal = {Biochemistry},
year = {2026},
month = sep,
doi = {10.1021/bi990565b},
url = {https://hal.science/hal-05741402v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Electrochemical and Spectroscopic Investigations of the Cytochrome bc 1 Complex from Rhodobacter capsulatus
AU - Frauke Baymann
AU - D. Robertson
AU - P. Dutton
AU - Werner Mäntele
PY - 2026
DA - 2026/09/07
JO - Biochemistry
DO - 10.1021/bi990565b
UR - https://hal.science/hal-05741402v1
AB - The cytochrome bc1-complex from Rhodobacter capsulatus was investigated by protein electrochemistry and VIS/IR spectroscopy. Infrared difference spectra, which represent redoxinduced conformational changes of cofactors and their protein environment, show signals of the hemes, the quinone Q i , and small conformational changes of the protein backbone. Furthermore band features were tentatively assigned to protonated aspartic or glutamic acids involved in the redox transition of each of the b-hemes, a proline in that of the [2Fe2S] protein and an arginine in that of cytochrome bH. The midpoint potential of the [2Fe2S] protein was determined for the first time at physiological temperature to be +290 mV at pH 8.7. The reduced minus oxidized difference extinction coefficients of the α-bands of the cytochromes were calculated to 11.5 mM⁻¹ cm⁻¹, 19 mM⁻¹ cm⁻¹ and 6.7 mM⁻¹ cm⁻¹ for cytochrome c₁, bH, and bL respectively. A novel method has been developed to quantify protonation reactions of the complex during the redox reactions of its cofactors by evaluation of the buffer signals in the mid-infrared region. Values will be discussed in relation to the pHdependence of the midpoint potentials.
SN - 0006-2960
SN - 1520-4995
ER -