EC Number   |
General Information |
Reference |
|---|
    1.10.3.9 | malfunction |
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 |
-, 765530 |
| 1.10.3.9 | malfunction |
PSII is highly sensitive to photoinhibiton in the psbL deletion mutant. The electron flow to plastoquinone in PSII is impaired in the psbJ deletion mutant |
714155 |
| 1.10.3.9 | more |
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 |
726103 |
| 1.10.3.9 | more |
identification of oxidized amino acid residues in the D1, D2 CP47, and CP43 proteins, in the vicinity of the Mn4O5Ca cluster active site of PS II, by mass spectrometry. The residues are modified by reactive oxygen species generated within the PS II complex |
724348 |
| 1.10.3.9 | more |
mechanism of proton-coupled quinone reduction in photosystem II, overview. The initial proton transfer to QB.- occurs from the protonated, D1-His252 to QB.- via D1-Ser264. The second proton transfer is likely to occur from D1-His215 to QBH- via an H-bond with an energy profile with a single well, resulting in the formation of QBH2 and the D1-His215 anion. The pathway for reprotonation of D1-His215- may involve bicarbonate, D1-Tyr246 and water in the QB site. Potential-energy profiles of the H-bond donor-acceptor pairs, overview |
726401 |
| 1.10.3.9 | more |
plastoquinol exogenously added to plastoquinone-depleted PSII membranes serves as efficient scavenger of 1O2, overview |
724408 |
| 1.10.3.9 | physiological function |
a darkadapted mutant lacking terminal oxidases with naturally reduced plastoquinone is characterized by slower QA-roxidation and O2 evolution rates and lower quantum yield of PSII primary photochemical reactions as compared to the wild type and succinate dehydrogenaselacking mutant, in which the plastoquinone pool remains oxidized in the dark. Light adaptation increases PSII primary photochemical reactions in all tested strains, with the greatest increase in in the mutant. Continuous illumination of mutant cells with low intensity blue light also increases PSII primary photochemical reactions and PSII functional absorption crosssection. This effect is almost absent in the wild type and succinate dehydrogenaselacking mutant |
741876 |
| 1.10.3.9 | physiological function |
cells grow increasingly faster at higher light intensities from low to high to extreme by escalating photoprotection via shifting from linear electron flow (PSII-LEF) to cyclic electron flow (PSII-CEF) with concomitant PSII charge separation from plastoquinone reduction (PSII-LEF) to plastoquinol oxidation (PSII-CEF). Low light-grown cells have unusually small antennae, use mainly PSII-LEF and convert 40% of PSII charge separations into O2. High light-grown cells have smaller antenna and lower PSII-LEF. Extreme light-grown cells have no LHCII antenna, minimal PSII-LEF, and a doubling time of 1.3 h |
741990 |
| 1.10.3.9 | physiological function |
molecular dynamics simulations of PSII embedded in the thylakoid membrane. In addition to the two known channels, a third channel for plastoquinone/plastoquinone diffusion is observed between the thylakoid membrane and the plastoquinone binding sites. In a promiscuous diffusion mechanism all three channels function as entry and exit channels. The exchange cavity serves as a plastoquinone reservoir |
743341 |
| 1.10.3.9 | physiological function |
photosystem II is a light-driven water-plastoquinone oxidoreductase. It produces molecular oxygen as an enzymatic product. Under a variety of stress conditions, reactive oxygen species are produced at or near the active site for oxygen evolution |
724348 |
