Phenolic Herbicides: Correlation between Lipophilicity and Increased Inhibitory Sensitivity of Thylakoids from Higher Plant Mutants

1986 ◽  
Vol 41 (9-10) ◽  
pp. 881-884 ◽  
Author(s):  
Jörg Durner ◽  
Andreas Thiel ◽  
Peter Böger
Keyword(s):  
Brassica Napus ◽  
Photosystem Ii ◽  
Partition Coefficient ◽  
Inhibitory Activity ◽  
Partition Coefficients ◽  
Higher Plants ◽  
Higher Plant

Abstract Pheonlic herbicides, being quite hydrophilic as compared to classical photosystem-II inhibitors do not exhibit a correlation between inhibitory activity and partition coefficient. Sensitivity against phenolic herbicides, however, as observed with atrazine-resistant thylakoids from higher plants mutants (Brassica napus) is increased by higher partition coefficients.

scholarly journals Electronic Structure of Tyrosyl D Radical of Photosystem II, as Revealed by 2D-Hyperfine Sublevel Correlation Spectroscopy

2021 ◽  
Vol 7 (9) ◽  
pp. 131
Author(s):  
Maria Chrysina ◽  
Georgia Zahariou ◽  
Nikolaos Ioannidis ◽  
Yiannis Sanakis ◽  
George Mitrikas
Keyword(s):  
Electronic Structure ◽  
Photosystem Ii ◽  
Water Oxidation ◽  
Spinacia Oleracea ◽  
Higher Plants ◽  
Correlation Spectroscopy ◽  
Oxygen Evolving Complex ◽  
Higher Plant ◽  
Proton Coupled Electron Transfer ◽  
S Oxidation

The biological water oxidation takes place in Photosystem II (PSII), a multi-subunit protein located in thylakoid membranes of higher plant chloroplasts and cyanobacteria. The catalytic site of PSII is a Mn4Ca cluster and is known as the oxygen evolving complex (OEC) of PSII. Two tyrosine residues D1-Tyr161 (YZ) and D2-Tyr160 (YD) are symmetrically placed in the two core subunits D1 and D2 and participate in proton coupled electron transfer reactions. YZ of PSII is near the OEC and mediates electron coupled proton transfer from Mn4Ca to the photooxidizable chlorophyll species P680+. YD does not directly interact with OEC, but is crucial for modulating the various S oxidation states of the OEC. In PSII from higher plants the environment of YD• radical has been extensively characterized only in spinach (Spinacia oleracea) Mn- depleted non functional PSII membranes. Here, we present a 2D-HYSCORE investigation in functional PSII of spinach to determine the electronic structure of YD• radical. The hyperfine couplings of the protons that interact with the YD• radical are determined and the relevant assignment is provided. A discussion on the similarities and differences between the present results and the results from studies performed in non functional PSII membranes from higher plants and PSII preparations from other organisms is given.

Photoreduction of NADP+ in Photosystem II of Higher Plants: Requirement for Manganese

1992 ◽  
Vol 47 (1-2) ◽  
pp. 57-62 ◽  
Author(s):  
Suleyman I. Allakhverdiev ◽  
Vyacheslav V. Klimov
Keyword(s):  
Photosystem Ii ◽  
Higher Plants ◽  
Complete Removal ◽  
Reaction Centers ◽  
Higher Plant ◽  
Ps Ii ◽  
Alternate Pathway ◽  
Manganese Extraction ◽  
Quinone Acceptor ◽  
Reduced State

Abstract The effects of reversible manganese extraction on NADP+ photoreduction were studied with higher plant subchloroplast preparations of photosystem II (PS II). Under anaerobic conditions, when the reaction centers (RCs) of PS II are “closed” (i.e. in the state [P680 Pheo] QA), and in the presence of ferredoxin-ferredoxin-NADP+ reductase, NADP+ reduction is observed at a rate of 0.8 -1.1 nmol/mg × chlorophyll × h. After complete removal of manganese from PS II, the rate of NADP+ reduction is reduced 40 - 50-fold. Upon the addition of Mn at a concentration of approx. 4 Mn atoms per reaction center, the NADP+ reduction is restored up to 85 -90% of the initial value. When half of this amount of Mn is combined with about 40 times of the equivalent concentration of other divalent ions (Ca2+, Sr2+, Mg2+ etc.) the reaction is also reactivated. Dinoseb (10-6 m) an inhibitor of electron transfer in PS II prevents NADP+ photoreduction. It is concluded that under conditions when the first quinone acceptor, QA, is in its reduced state (QA-) electrons are transferred from reduced pheophytin (Pheo·̅) to NADP+, indicating that PS II can reduce NADP+ without the participation of PS I. On the basis of these and literature data, an alternate pathway for electron phototransfer in PS II reaction centers of higher plants is suggested. Some problems concerning the Z-scheme are discussed.

scholarly journals High-resolution model of Arabidopsis Photosystem II reveals the structural consequences of digitonin-extraction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
André T. Graça ◽  
Michael Hall ◽  
Karina Persson ◽  
Wolfgang P. Schröder
Keyword(s):  
High Resolution ◽  
Photosystem Ii ◽  
Metal Ion ◽  
Higher Plants ◽  
Protein Complexes ◽  
Early Stage ◽  
Model Organism ◽  
Higher Plant ◽  
High Resolution Structure ◽  
Resolution Structure

AbstractIn higher plants, the photosynthetic process is performed and regulated by Photosystem II (PSII). Arabidopsis thaliana was the first higher plant with a fully sequenced genome, conferring it the status of a model organism; nonetheless, a high-resolution structure of its Photosystem II is missing. We present the first Cryo-EM high-resolution structure of Arabidopsis PSII supercomplex with average resolution of 2.79 Å, an important model for future PSII studies. The digitonin extracted PSII complexes demonstrate the importance of: the LHG2630-lipid-headgroup in the trimerization of the light-harvesting complex II; the stabilization of the PsbJ subunit and the CP43-loop E by DGD520-lipid; the choice of detergent for the integrity of membrane protein complexes. Furthermore, our data shows at the anticipated Mn4CaO5-site a single metal ion density as a reminiscent early stage of Photosystem II photoactivation.

scholarly journals High-resolution model of Arabidopsis Photosystem II reveals the structural consequences of digitonin-extraction

2021 ◽  
Author(s):  
André T. Graça ◽  
Michael Hall ◽  
Karina Persson ◽  
Wolfgang P. Schröder
Keyword(s):  
High Resolution ◽  
Photosystem Ii ◽  
Metal Ion ◽  
Higher Plants ◽  
Protein Complexes ◽  
Early Stage ◽  
Model Organism ◽  
Higher Plant ◽  
High Resolution Structure ◽  
Resolution Structure

AbstractIn higher plants, the photosynthetic process is performed and regulated by Photosystem II (PSII). Arabidopsis thaliana was the first higher plant with a fully sequenced genome, conferring it the status of a model organism; nonetheless, a high-resolution structure of its Photosystem II is missing. We present the first Cryo-EM high-resolution structure of Arabidopsis PSII supercomplex with average resolution of 2.79 Å, an important model for future PSII studies. The digitonin extracted PSII complexes demonstrate the importance of: the LHG2630-lipid-headgroup in the trimerization of the light-harvesting complex II; the stabilization of the PsbJ subunit and the CP43-loop E by DGD520-lipid; the choice of detergent to maintain the integrity of membrane protein complexes. We propose that PsbW and PsbH subunits participate in the phospho-signalling dimerization of the complex, important to the assembly/repair processes of Photosystem II. Furthermore, our data shows at the anticipated Mn4CaO5-site a single metal ion density as a reminiscent early stage of PSII photoactivation.

Differential Inhibition and Rephasing of Photosystem II Electron Acceptor Side by Monohalogenated Acetates of Different Hydrophobicity

1992 ◽  
Vol 47 (9-10) ◽  
pp. 711-716 ◽  
Author(s):  
Chunhe Xu ◽  
Yong Zhu ◽  
Govindjee
Keyword(s):  
Photosystem Ii ◽  
Partition Coefficient ◽  
Reaction Center ◽  
Electron Acceptor ◽  
Inhibitory Activity ◽  
Differential Inhibition ◽  
Ps Ii ◽  
Acceptor Side ◽  
Unusual Effect

We demonstrate here that monohalogenated acetates (MFA , monofluoroacetate; M CA, monochloroacetate; MBA, monobromoacetate) are unique probes of the electron acceptor side of the photosystem II (PS II) reaction center: (1) they differentially inhibit the reoxidation of the reduced primary plastoquinone electron acceptor, QA-, by the secondary plastoquinone electron acceptor QB, and increase the equilibrium [QA-] in the order: MBA ≳ M CA > MFA; and (2) M CA and MBA rephase the PS II electron acceptor side, a rather unusual effect. This results in flash number dependence of [QA-] with maxima at even flashes to change to odd flashes. Furthermore, we demonstrate a correlation between the inhibitory activity of the halogenated acetates with their hydrophobicity (i.e., partition coefficient).

Partition Coefficient Ratios and Tumour Perfusion Studied with 85mKr and 133Xe

1987 ◽  
Vol 26 (06) ◽  
pp. 253-257
Author(s):  
M. Mäntylä ◽  
J. Perkkiö ◽  
J. Heikkonen
Keyword(s):  
Partition Coefficient ◽  
Partition Coefficients ◽  
Regional Blood Flow ◽  
Blood Perfusion ◽  
Compartmental Analysis ◽  
Malignant Tumour ◽  
Mean Value ◽  
Perfusion Rate ◽  
Biological Variables ◽  
The Mean

The relative partition coefficients of krypton and xenon, and the regional blood flow in 27 superficial malignant tumour nodules in 22 patients with diagnosed tumours were measured using the 85mKr- and 133Xe-clearance method. In order to minimize the effect of biological variables on the measurements the radionuclides were injected simultaneously into the tumour. The distribution of the radiotracers was assumed to be in equilibrium at the beginning of the experiment. The blood perfusion was calculated by fitting a two-exponential function to the measuring points. The mean value of the perfusion rate calculated from the xenon results was 13 ± 10 ml/(100 g-min) [range 3 to 38 ml/(100 g-min)] and from the krypton results 19 ± 11 ml/(100 g-min) [range 5 to 45 ml/(100 g-min)]. These values were obtained, if the partition coefficients are equal to one. The equations obtained by using compartmental analysis were used for the calculation of the relative partition coefficient of krypton and xenon. The partition coefficient of krypton was found to be slightly smaller than that of xenon, which may be due to its smaller molecular weight.

Interphase distribution of 2-furylethylenes

1985 ◽  
Vol 50 (8) ◽  
pp. 1642-1647 ◽  
Author(s):  
Štefan Baláž ◽  
Anton Kuchár ◽  
Ernest Šturdík ◽  
Michal Rosenberg ◽  
Ladislav Štibrányi ◽  
...  
Keyword(s):  
Partition Coefficient ◽  
Partition Coefficients ◽  
Transport Rate ◽  
Phase System ◽  
Two Phase ◽  
Interphase Distribution ◽  
Distribution Kinetics ◽  
System 1 ◽  
Kinetics Of

The distribution kinetics of 35 2-furylethylene derivatives in two-phase system 1-octanol-water was investigated. The transport rate parameters in direction water-1-octanol (l1) and backwards (l2) are partition coefficient P = l1/l2 dependent according to equations l1 = logP - log(βP + 1) + const., l2 = -log(βP + 1) + const., const. = -5.600, β = 0.261. Importance of this finding for assesment of distribution of compounds under investigation in biosystems and also the suitability of the presented method for determination of partition coefficients are discussed.

scholarly journals Biochemical composition and organization of higher plant photosystem II light-harvesting pigment-proteins.

1991 ◽  
Vol 266 (25) ◽  
pp. 16745-16754 ◽  
Author(s):  
G.F. Peter ◽  
J.P. Thornber
Keyword(s):  
Photosystem Ii ◽  
Biochemical Composition ◽  
Light Harvesting ◽  
Higher Plant

scholarly journals Crystal structure of the PsbQ protein of photosystem II from higher plants

EMBO Reports ◽  
2003 ◽  
Vol 4 (9) ◽  
pp. 900-905 ◽  
Author(s):  
Vito Calderone ◽  
Michela Trabucco ◽  
Andreja Vujičić ◽  
Roberto Battistutta ◽  
Giorgio Mario Giacometti ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Photosystem Ii ◽  
Higher Plants

scholarly journals Use of protein cross-linking and radiolytic footprinting to elucidate PsbP and PsbQ interactions within higher plant Photosystem II

2014 ◽  
Vol 111 (45) ◽  
pp. 16178-16183 ◽  
Author(s):  
Manjula P. Mummadisetti ◽  
Laurie K. Frankel ◽  
Henry D. Bellamy ◽  
Larry Sallans ◽  
Jost S. Goettert ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Cross Linking ◽  
Higher Plant ◽  
Protein Cross Linking
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