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Proton transfer in the photosynthetic reaction center of Blastochloris viridis
Author(s) -
Kozlova Maria A.,
Juhnke Hanno D.,
Cherepanov Dmitry A.,
Lancaster C. Roy D.,
Mulkidjanian Armen Y.
Publication year - 2008
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.12.010
Subject(s) - photosynthetic reaction centre , ubiquinol , chemistry , flash (photography) , proton , kinetics , reaction rate constant , analytical chemistry (journal) , activation energy , photosynthesis , photochemistry , electron transfer , organic chemistry , physics , biochemistry , nuclear physics , optics , cytochrome c , quantum mechanics , coenzyme q – cytochrome c reductase , mitochondrion
Photosynthetic reaction centers of Blastochloris viridis require two quanta of light to catalyse a two‐step reduction of their secondary ubiquinone Q B to ubiquinol. We employed capacitive potentiometry to follow the voltage changes that were caused by the accompanying transmembrane proton displacements. At pH 7.5 and 20 °C, the Q B ‐related voltage generation after the first flash was contributed by a fast, temperature‐independent component with a time constant of ∼30 μs and a slower component of ∼200 μs with activation energy ( E a ) of 50 kJ/mol. The kinetics after the second flash featured temperature‐independent components of 5 μs and 200 μs followed by a component of 600 μs with E a ∼ 60 kJ/mol.