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Photoinduced electron transfer from carboxymethylated cytochrome c to plastocyanin
M Karpefors1, M T Wilson, P Brzezinski
1Department of Biochemistry and Biophysics, University of Göteborg and Chalmers University of Technology (Medicinaregatan 9C), P.O. Box 462, SE-405 30 Göteborg, Sweden.
Abstract:
Photoinduced electron transfer from cytochrome c to plastocyanin was investigated using a novel method. Reduced carboxymethylated cytochrome c (CmCyt c), with carbon monoxide bound to the heme iron, and oxidized plastocyanin were mixed. At 1 mM CO the reduced state of CmCyt c is stabilized by about 350 meV. After flash photolysis of CO the apparent redox potential of CmCyt c drops resulting in electron transfer to plastocyanin. The electron transfer characteristics were investigated at approximately 30 different wavelengths in the range 390-460 nm. A global fit of the data showed that the electron transfer rate is 960+/-30 s-1 at pH 7.