title: Modification by immobilization of the microenvironment of chromatophores of Rhodopseudomonas capsulata. The influence on light-induced ADP phosphorylation coupled to cyclic electron transport.
abstract: Rhodopseudomonas capsulata chromatophores were immobilized with a co-crosslinking method. Immobilization was used as a tool for a defined modification of the chromatophore environment to study ATP production over a long period of time. The light-induced phosphorylation of ADP as a function of time was studied with chromatophores under different conditions: (a) native chromatophores with and without the hexokinase ATP-trapping system; (b) immobilized chromatophores without hexokinase, with the enzyme added in the bulk solution and with the enzyme co-immobilized in the matrix. The overall amount of ATP produced as a function of ADP concentration was studied for native and immobilized chromatophores. The global phosphorylation performed was also studied as a function of the amount of biological material used. The results can be explained by an effect of the ATP/ADP ratio. The results given by the immobilization show that the important point is not the ATP/ADP ratio in the bulk solution but the ratio value in the microenvironment of the chromatophore itself.
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D020130:Bacterial Chromatophores / Q000378:metabolism*; D004579:Electron Transport; D004800:Enzymes, Immobilized / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D007700:Kinetics; D008027:Light; D010085:Oxidative Phosphorylation; D012241:Rhodopseudomonas / Q000378:metabolism*
chemical_list: D004800:Enzymes, Immobilized; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D006593:Hexokinase