• It specifically plays an inhibitory role in photosystem II (PSII) by blocking the flow of electrons from QA to QB. (wikipedia.org)
  • Photosystem II (PSII) is the initial site of photosynthetic electron transfer by water oxidation. (elifesciences.org)
  • In photosynthetic organisms, maintenance of photosynthetic light reaction is manifested by so called Photosystem II (PSII) repair system, where the reaction center protein D1 is targeted to photo-oxidative damage and rapidly degraded by the processive protease FtsH. (elifesciences.org)
  • The first step of photosynthetic electron transfer in the thylakoid membrane occurs at Photosystem II (PSII), where light energy absorbed by P 680 chlorophyll molecules drives water oxidation, and electron is transferred to plastoquinone. (elifesciences.org)
  • The instrument uses an array of software-controlled excitation light sources operating in pulse/DC mode to manipulate the state of photosynthetic reaction centers while measuring changes in the fluorescence signal emanating from Photosystem II chlorophyll antenna. (soliense.com)
  • The difference between Photosystem II and the bacterial reaction center is the source of the electron that neutralizes the pair of chlorophyll a molecules. (goldenssport.com)
  • The structure of Photosystem II is remarkably similar to the bacterial reaction center, and it is theorized that they share a common ancestor. (goldenssport.com)
  • We employed digital RGB imaging to study shoot growth, and chlorophyll (Chl) fluorescence imaging (CFIM) to analyze various parameters of plant photosystem II (PSII) efficiency. (biomedcentral.com)
  • The light-dependent reactions begin in photosystem II. (sciencespo-lille.com)
  • At 27/22 ◦ C (day/night), drought stress led to the oxidation of the reaction center of the chlorophyll of PSI (P700), and also led to decreases in the quantum efficiencies of photosystem II (PSII) and PSI, and a reduction of the primary quinone electron acceptor of PSI. (elsevierpure.com)
  • The reaction center chlorophyll (or the primary electron donor) of photosystem II that is most reactive and best in absorbing light at wavelength of 680 nm. (e-cyanobacterium.org)
  • The cytochrome b6f complex occupies a central position in the sequence of photosynthetic electron transport carriers, oxidizing plastoquinol (PQH 2) and providing the electron transfer connection between the two reaction center complexes, PS II and PS I, to which H + transfer is coupled, thus contributing to the trans-membrane. (rehabsociety.org.hk)
  • In plant photosynthetic membranes PSII forms large multisubunit supercomplexes, containing a dimeric core and up to four light-harvesting complexes (LHCs), which act as antenna proteins. (hal.science)
  • Unlike reaction centers, LH complexes exhibit a large variability among photosynthetic organisms. (polivkalab.cz)
  • A membrane enriched in complexes formed of reaction centers, accessory pigments and electron carriers, in which photosynthetic reactions take place. (e-cyanobacterium.org)
  • The amount of fluorescence detected in the dark is the background level when all reaction centers are open and is designated F 0 or minimal fluorescence. (weebly.com)
  • The top of the peak, when all of the reaction centers are closed, is labeled F m or maximal fluorescence. (weebly.com)
  • Measurements of chlorophyll fluorescence emission and excitation spectra at 77 K provided strong evidence that there was little or no difference in the composition or function of PSI or PSII between the two sets of plants, implying that changes in photosynthetic stoichiometry are primarily responsible for the observed differences in photosynthetic function. (ckbiobank.org)
  • To maintain photosynthetic activity, the PSII reaction center protein D1, which is the primary target of unavoidable photo-oxidative damage, is efficiently degraded by FtsH protease. (elifesciences.org)
  • Further characterization of Trp-14 using chloroplast transformation in Chlamydomonas indicated that substitution of D1 Trp-14 to Phe, mimicking Trp oxidation enhanced FtsH-mediated D1 degradation under high light, although the substitution did not affect protein stability and PSII activity. (elifesciences.org)
  • The work supports a role for chemical modification in the recognition and subsequent degradation of a key protein subunit of PSII by a bacterial-type protease, suggesting that tryptophan oxidation of components of the photosynthetic apparatus after high light stress plays a critical role in initiating the PSII repair system. (elifesciences.org)
  • In the bacterial reaction center, the electron is obtained from a reduced compound haem group in a cytochrome subunit or from a water-soluble cytochrome-c protein. (goldenssport.com)
  • Additionally, the PSBS protein involved in NPQ and the minor PSII antenna protein LHCB4 were probed. (agrisera.com)
  • the double reduced secondary quinone acceptor Qb2- is protonated plastoquinol and released from the Qb-binding pocket of the PSII D1 protein to plastoquinon pool. (e-cyanobacterium.org)
  • Light-induced signals originating from both donor and acceptor cofactors demonstrate that electron transfer occurs through both branches of cofactors in the pseudo- C 2 symmetric reaction center (RC). (copernicus.org)
  • PSII acceptor side carotenoid quenching (1) . (soliense.com)
  • The efficiency of transfer of excitation energy from the chromophore that absorbed the photon to the reaction centre is very high (Collins et al. (harvard.edu)
  • A photosystem that contains a pheophytin-quinone reaction center with associated accessory pigments and electron carriers. (e-cyanobacterium.org)
  • The decrease of PSII activity was mainly due to the reduction in the activity of oxygenevolving complex (OEC) on donor side of PSII and the blockage of electron transfer from Q A to Q B on receptor side of PSII. (cje.net.cn)
  • The donor side of PSII was more sensitive to salt stress than the receptor side of PSII. (cje.net.cn)
  • MT application can alleviate the damage on tomato caused by salt stress through balancing the electron transfer on donor side, receptor side and reaction center of PSII. (cje.net.cn)
  • First, the transfer of an electron from BPh− to P960+ is relatively slow compared to two other redox reactions in the reaction center. (goldenssport.com)
  • The LH complex absorbs light energy and funnels it into the reaction center where the charge separation takes place. (polivkalab.cz)
  • PSII core complex is formed by two reaction center proteins D1 (PsbA) and D2 (PsbD), along with intrinsic antenna CP43 (PsbC) and CP47 (PsbB). (elifesciences.org)
  • Photosynthetic apparatus of all photosynthetic organisms contains two vital components needed for the light reactions: a light-harvesting (LH) antenna and a reaction center. (polivkalab.cz)
  • The decreased chlorophyll a / b ratio could be explained by the relative enrichment of light-harvesting antenna to reaction center with leaf senescence. (chinacrops.org)
  • And finally, additional safeguard molecules 'deactivate' compounds that could otherwise mediate damaging reactions. (elifesciences.org)
  • We located all 35 chlorophylls of the core region based on the cyanobacterial PSII structure, whose positioning is highly conserved, as well as all the chlorophylls of the LHCII S and M trimers. (hal.science)
  • 0.8 electrons per absorbed photon in PSII (Falkowski and Raven 2007 Johnsen and Sakshaug 2007 Hogewoning et al. (harvard.edu)
  • We found that the slug Elysia timida induces changes to the photosynthetic light reactions of the chloroplasts it steals from the alga Acetabularia acetabulum . (elifesciences.org)
  • Furthermore, Trp-14 to Phe modification appeared to have an additive effect in the interaction between FtsH and PSII core in vivo. (elifesciences.org)
  • In the 1960s, Roderick Clayton was the first to purify the reaction center complex from purple bacteria. (goldenssport.com)
  • In the center of the oxygen evolving complex (OEC) was attacked by studies by Yachandra and coworkers (17-19), it was concluded a manganese-bridging oxo group. (lu.se)
  • In addition, the ability of PSII reaction center to harvest and utilize light energy, the concentration of reaction centers (expressed as per unit leaf area) and the ratio of excitation energy to absorbed energy were all decreased. (cje.net.cn)
  • The content of PS II reaction centres was unchanged on a leaf area basis, but there was evidence for increases in the relative levels of other light harvesting proteins, notably CP26, associated with PS II, and Lhca4, associated with PS I. Electron microscopy showed the presence of grana. (ox.ac.uk)
  • Molecular dynamics simulation of PSII implies that both Trp-14 oxidation and Phe substitution cause fluctuation of D1 N-terminal tail. (elifesciences.org)
  • He was Head of the Department of Molecular Biology and Pharmacology from 1991-2004 before becoming the founding Director of a University-wide, Center for Genome Sciences and Systems Biology. (amphilsoc.org)
  • FIRe parameters were set to measure single turnover flash of PSII reaction centers (single closure event) with a sample delay of 100, and a total of 50 samples (Gorbunov and Falkowski 2004). (bco-dmo.org)
  • Together, our results suggest that the Trp oxidation at its N-terminus of D1 may be one of the key oxidations in the PSII repair, leading to processive degradation by FtsH. (elifesciences.org)
  • Here, we characterized oxidative modification of tryptophan (Trp) residues in the PSII core, and hypothesize that the oxidation of N-terminal Trp is one of the key oxidations in the PSII repair, likely enhancing D1's accessibility to FtsH. (elifesciences.org)
  • In those pathways, FNR however catalyses the opposite reaction, namely the production of reduced Fd 4 and is thus sometimes classified as heterotrophic FNR. (nature.com)
  • Photoinhibition occurs when the reaction centers start becoming damaged and must be broken down to be repaired. (weebly.com)
  • These results indicate that the drought stress responses of the respective PET reactions are closely associated with each other in the oxidization of P700 and that such responses are stimulated at high temperatures. (elsevierpure.com)
  • Landsberg erecta was grown under light regimes of differing spectral qualities, which results in differences in the stoichiometries of the two photosynthetic reaction centres. (ckbiobank.org)
  • For example, overwintering evergreens have developed so-called sustained non-photochemical quenching (reviewed, e.g., by Verhoeven [ 4 ]) as a protection mechanism against absorbed light which is in excess with respect to the capacity of the carbon photosynthetic reactions and which is decreased during winter. (biomedcentral.com)
  • This saturating pulse is a very strong light, providing a plethora of photons and rendering all of the reaction centers closed. (weebly.com)
  • The review is summarized and systematized the published data on the multicomponent reactions of ethyl trifluoroacetoacetate, carbonyl compounds (aldehydes and ketones), and nucleophilic reagents. (researchgate.net)
  • Powered by light, this enzyme catalyses the chemically and thermodynamically demanding reaction of water splitting. (goldenssport.com)
  • Treatment with 96 kJ·m −2 ·d −1 enhanced ultraviolet-B radiation improved Rubisco activity by increasing the expression of the Rubisco large and small subunit genes, thereby enhancing the CO 2 -fixing capacity and dark reaction capacity of leaves. (ashs.org)
  • The net photosynthetic rate (P n ), photosynthetic pigment content, Hill reaction activity, and photochemical quenching coefficient (qP) of the treated leaves showed significantly higher values than those of the control leaves. (ashs.org)
  • 55 It was found that the solventfree reaction of ETFAA 1a, benzaldehyde, and ammonium acetate at 100 C proceeded with the loss of the water molecule to aff ord partially dehydrated 2-hydroxy-2,6-bis(trifl uoromethyl)-1,2,3,4-tetrahydropyridine-3,5-dicarboxylate 6. (researchgate.net)
  • This process, known as Mehler reaction, results in formation of H 2 O 2 which is generated by the superoxide dismutase (SOD) and converted into water and oxygen by ascorbate peroxidase 9 . (nature.com)
  • Mehler reaction, or water-water cycle, allows functionality of the CET and subsequent synthesis of ATP needed for the Calvin cycle, which finally oxidizes NADPH to re-establish LET 5 . (nature.com)
  • The state of the reaction centers are important. (weebly.com)