169 research outputs found
Selective Inhibition by Actinomycin D of the Synthesis in Photosynthetic and Non-photosynthetic Enzymes During the Greening of Etiolated Bean Leaves
Energy transduction in photosynthetic bacteria III. Coincidence of coupling factor of photosynthesis and respiration in Rhodopseudomonas capsulata
The multifarious role of ubiquinone in bacterial chromatophores
The role of ubiquinone in the electron transport and ATP synthesis in photosyntetic membranes isolated from Rhodobacter is discussed
Light-induced proton gradients and internal volumes in chromatophores of Rhodopseudomonas sphaeroides
Energy transduction in photosynthetic bacteria V. Role of coupling factor ATPase in energy conversion as revealed by light or ATP-induced quenching of atebrine fluorescence
Relevance of the Protein-Lipid Interaction on the Functioning of the Bacterial Reaction Center
Structural requirements of quinone coenzymes for endogenous and dye-mediated coupled electron transport in bacterial photosynthesis.
Electron transport in continuous light has been investigated in chromatophores of Rhodopseudomonas capsulata. Ala pho+, depleted in ubiquinone-10 and subsequently reconstituted with various ubiquinone homologs and analogs. In addition the restoration of electron transport in depleted chromatophores by the artificial redox compounds N-methylphenazonium methosulfate and N,N,N',N'-tetramethyl-p-phenylenediamine was studied. The following pattern of activities was obtained: (1) Reconstitution of cyclic photophosphorylation with ubiquinone-10 was saturated at about 40 ubiquinone molecules per reaction center. (2) Reconstitution by ubiquinone homologs was dependent on the length of the isoprenoid side chain and the amount of residual ubiquinone in the extracted chromatophores. If two or more molecules of ubiquinone-10 per reaction center were retained, all homologs with a side chain longer than two isoprene units were as active as ubiquinone-10 in reconstitution, and the double bonds in the side chain were not required. If less than two molecules per reaction center remained, an unsaturated side chain longer than five units was necessary for full activity. Plastoquinone, alpha-tocopherol, and naphthoquinones of the vitamin K series were relatively inactive in both cases. (3) All ubiquinone homologs, also ubiquinone-1 and -2, could be reduced equally well by the photosynthetic reaction center, as measured by light-induced proton binding in the presence of antimycin A and uncoupler. Plastoquinone was found to be a poor electron acceptor. (4) Photophosphorylation could be reconstituted by N-methylphenazonium methosulfate as well as by N,N,N',N'-tetramethyl-p-phenylenediamine in an antimycin-insensitive way, if more than two ubiquinones per reaction center remained. These compounds were active also in more extensively extracted particles reconstituted with ubiquinone-1, which itself was inactive
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