Photosysem II: where does the light-induced voltage come from?
Photosystem II (PS II) is a biological energy transducer. The enzyme catalyses the light-driven oxidation of water and reduction of plastoquinone. The aim of this work was to review the mechanisms of electrical events in PS II. The major contribution to the total photoelectric response is due to the charge-separation between the primary chlorophyll donor P680 and quinone acceptor QA accompanied by re-reduction of P680+ by tyrosine residue YZ. The remaining part of the membrane potential is believed to be associated mainly with electron and proton transfer events due to the S-state transitions of the oxygen-evolving complex and proton uptake associated with protonation of the doubly reduced secondary quinone acceptor QB. Under certain non-physiological conditions, some other electrogenic reactions are observed, namely: proton-coupled electron transfer between QA and non-heme Fe3+ and electron transfer from the protein-water interface to the YZ radical in the presence of artificial electron donors. These data may provide a good platform for further development of artificial photosynthetic constructs and bio-inspired catalysts.
A.N. Belozersky Institute of Physical-Chemical Biology, Moscow State University, 119991 Moscow, Leninskie gory, Russia. mamedov@genebee.msu.su
Mahir D
MD
Mamedov
Vasily N
VN
Kurashov
Dmitry A
DA
Cherepanov
Alexey Yu
AY
Semenov
D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism; D004579:Electron Transport / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D008956:Models, Chemical; D055668:Photochemical Processes / Q000528:radiation effects*; D010788:Photosynthesis / Q000528:radiation effects*; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism*; D010971:Plastoquinone / Q000737:chemistry / Q000378:metabolism; D014867:Water / Q000737:chemistry / Q000378:metabolism
D045332:Photosystem II Protein Complex; D014867:Water; D002734:Chlorophyll; D010971:Plastoquinone