title: Macromolecular crowding and its influence on possible reaction mechanisms in photosynthetic electron flow.
abstract: The diffusion of plastoquinol and its binding to the Qo site of the cyt bf complex in the course of photosynthetic electron transport was studied by following the sigmoidal flash-induced re-reduction kinetics of P700 after previous oxidation of the intersystem electron carriers. The data resulting from these experiments were matched with a simulation of electron transport using Monte Carlo techniques. The simulation was able to account for the experimental observations. Two different extreme cases of reaction mechanism at the Qo site were compared: a diffusion limited collisional mechanism and a non-diffusion limited tight binding mechanism. Assuming a tight binding mechanism led to best matches due to the high protein density in thylakoids. The varied parameters resulted in values well within the range of published data. The results emphasise the importance of structural characteristics of thylakoids in models of electron transport.
authors: Max-Planck-Institute for Biophysical Chemistry, Theoretical and Computational Biophysics Department, Am Fassberg 11, D-37077 Goettingen, Germany. ira@germanynet.de
authors: I G
authors: IG
authors: Tremmel
authors: E
authors: E
authors: Weis
authors: G D
authors: GD
authors: Farquhar
mesh_terms: D000465:Algorithms; D002734:Chlorophyll / Q000378:metabolism; D004579:Electron Transport; D004734:Energy Metabolism; D007700:Kinetics; D008954:Models, Biological; D010788:Photosynthesis / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism; D010944:Plants / Q000378:metabolism*; D010971:Plastoquinone / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D002734:Chlorophyll; C001785:chlorophyll P 700; D010971:Plastoquinone