Measurement of the redox state of the ubiquinone pool in Rhodobacter capsulatus membrane fragments |
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Authors: | D Zannoni A L Moore |
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Affiliation: | Department of Biology, University of Bologna, Italy. |
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Abstract: | The dependence of the respiratory rate on the redox poise of the quinone pool was investigated in wild type and mutant membranes of Rhodobacter capsulatus. A linear relationship has been found between these two parameters only when succinate was oxidized by the bc1 complex. Conversely, a marked nonlinear relationship was observed between the Q-pool reduction level and the respiratory rate when O2 uptake occurred via the alternative oxidase. In addition, it was found that this latter pathway was not engaged until Q-pool reduction level reached approximately 25%. These results are discussed within the framework of a homogeneous pool regulating both photosynthetic and respiratory fluxes. |
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