Contains chlorophyll a, beta-carotene, pheophytin, plastoquinone, a Mn4Ca cluster, heme and non-heme iron. Four successive photoreactions, resulting in a storage of four positive charges, are required to oxidize two water molecules to one oxygen molecule.
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SYSTEMATIC NAME
IUBMB Comments
H2O:plastoquinone reductase (light-dependent)
Contains chlorophyll a, beta-carotene, pheophytin, plastoquinone, a Mn4Ca cluster, heme and non-heme iron. Four successive photoreactions, resulting in a storage of four positive charges, are required to oxidize two water molecules to one oxygen molecule.
photosystem II catalyzes the light-induced transfer of electrons from water to plastoquinone accompanied by the net transport of protons from the cytoplasm (stroma) to the lumen, the production of molecular oxygen and the release of plastoquinol into the membrane phase
photosystem II is a large homdimeric protein-cofactor complex consisting of 20 protein subunits, 35 chlorophyll a molecules and 12 carotenoid molecules, 25 integral lipids and 1 chloride ion per monomer
photosystem II is a large homdimeric protein-cofactor complex consisting of 20 protein subunits, 35 chlorophyll a molecules and 12 carotenoid molecules, 25 integral lipids and 1 chloride ion per monomer
photosystem II has two bound plastoquinones, QA and QB, which act as sequential electron acceptors. QA is tightly bound and acts as a one electron carrier while QB undergoes two sequential one-electron reduction steps
photosystem II is a large homdimeric protein-cofactor complex consisting of 20 protein subunits, 35 chlorophyll a molecules and 12 carotenoid molecules, 25 integral lipids and 1 chloride ion per monomer
photosystem II is a large homdimeric protein-cofactor complex consisting of 20 protein subunits, 35 chlorophyll a molecules and 12 carotenoid molecules, 25 integral lipids and 1 chloride ion per monomer
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GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
malfunction
Thermosynechococcus vestitus
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in the purified photosystem II lacking the PsbJ subunit (DELTAPsbJ-PSII) an active Mn4CaO5 cluster is present in 60-70% of the centers. In these centers, although the forward electron transfer seems not affected, the Em of the secondary quinone acceptor QB/QB(-) couple increases by more than 120 mV , thus disfavoring the electron coming back on primary quinone acceptor QA. The increase of the energy gap between QA/QA(-) and QB/QB(-) could contribute in a protection against the charge recombination between the donor side and QB(-), identified at the origin of photoinhibition under low light, and possibly during the slow photoactivation process
calculations at the molecular orbital-MP2/6-31G level using PSII models deduced from the X-ray structure of the PSII complexes from Thermosynechococcus elongatus, molecular interactions of the quinone electron acceptors QA, QB, and QC in photosystem II by the fragment molecular orbital method, arrangement of electron-transfer cofactors in PSII, modelling, overview
photosystem II (PSII), the oxygen-evolving enzyme, consists of 17 trans-membrane and 3 extrinsic membrane proteins. Other subunits bind to PSII during assembly, like Psb27, Psb28, and Tsl0063
modeling of the binding of lipoprotein Psb27 to the PSII surface in a region that is occupied by subunit PsbV in the mature complex. Psb27 is localized on the PSII surface adjacent to the large lumenal domain of light-harvesting protein CP43. Additional contacts associate Psb27 with light-harvesting protein CP47 and the C-termini of subunits PsbA and PsbB
molecular dynamics simulations of the complete PSII complex embedded in a lipid bilayer. PSII in the presence of plastoquinol shows a distinct dynamic behaviour which causes disruption of the interactions seen in the PSII-plastoquinone complex and leads to release of plastoquinol from the binding pocket. Displacement of plastoquinol closes the second water channel. Residue D1-Ser264 has a pivotal role in modulating the dynamics of the plastoquinone binding pocket and plastoquinol-plastoquinone exchange via its interaction with residue D1-His252
mutation in protein D1. Mutant displays a severe and persistent hampering of the QA-QB electron transfer resulting in a delay of the plastoquinone pool reduction rate