Regulation of photosystem II by metabolic and environmental factors

1989 ◽  
Vol 323 (1216) ◽  
pp. 269-279 ◽  
Keyword(s):  
Electron Transport ◽  
Higher Plants ◽  
Photosynthetic Electron Transport ◽  
Thylakoid Membranes ◽  
Internal Factors ◽  
Regulatory Processes ◽  
Quenching Analysis ◽  
Intact Chloroplasts ◽  
Rate Of Dissipation

The thylakoid membranes of higher plants possess several mechanisms that control both the distribution and rate of dissipation of absorbed light. These mechanisms, which allow regulation of photosynthetic electron transport in response to alteration in external and internal factors, can be observed as the various processes that quench chlorophyll fluorescence. By using the 'light-doubling techniques’, together with analysis of quenching relaxation, it is possible to assess quantitatively the extents of these regulatory processes and to allow their interrelations to be studied. These techniques can be applied to in vitro systems or to leaves, and can be particularly useful when applied with electron-transport measurements and when models are used to aid interpretation. Results of quenching analysis at different light intensities in isolated thylakoids, intact chloroplasts, protoplasts, algae and leaves of a variety of species are presented.

scholarly journals Synthesis and Biological Evaluation of 2-Hydroxy-3-[(2-aryloxyethyl)amino]propyl 4-[(Alkoxycarbonyl)amino]benzoates

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Jan Tengler ◽  
Iva Kapustíková ◽  
Matúš Peško ◽  
Rodney Govender ◽  
Stanislava Keltošová ◽  
...  
Keyword(s):  
Electron Transport ◽  
Conformational Changes ◽  
Spinacia Oleracea ◽  
Photosynthetic Electron Transport ◽  
Thylakoid Membranes ◽  
Biological Evaluation ◽  
Mycobacterial Species ◽  
Monocytic Leukaemia ◽  
Synthesis And Biological Evaluation

A series of twenty substituted 2-hydroxy-3-[(2-aryloxyethyl)amino]propyl 4-[(alkoxycarbonyl)amino]benzoates were prepared and characterized. As similar compounds have been described as potential antimycobacterials, primaryin vitroscreening of the synthesized carbamates was also performed against two mycobacterial species. 2-Hydroxy-3-[2-(2,6-dimethoxyphenoxy)ethylamino]-propyl 4-(butoxycarbonylamino)benzoate hydrochloride, 2-hydroxy-3-[2-(4-methoxyphenoxy)ethylamino]-propyl 4-(butoxycarbonylamino)benzoate hydrochloride, and 2-hydroxy-3-[2-(2-methoxyphenoxy)ethylamino]-propyl 4-(butoxycarbonylamino)benzoate hydrochloride showed higher activity againstM. aviumsubsp.paratuberculosisandM. intracellularethan the standards ciprofloxacin, isoniazid, or pyrazinamide. Cytotoxicity assay of effective compounds was performed using the human monocytic leukaemia THP-1 cell line. Compounds with predicted amphiphilic properties were also tested for their effects on the rate of photosynthetic electron transport (PET) in spinach (Spinacia oleraceaL.) chloroplasts. All butyl derivatives significantly stimulated the rate of PET, indicating that the compounds can induce conformational changes in thylakoid membranes resulting in an increase of their permeability and so causing uncoupling of phosphorylation from electron transport.

scholarly journals Photosynthetic electron transport in thylakoid preparations from two marine red algae (Rhodophyta)

1983 ◽  
Vol 210 (2) ◽  
pp. 583-589 ◽  
Author(s):  
A C Stewart ◽  
A W D Larkum
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Red Algae ◽  
Higher Plants ◽  
Outer Part ◽  
Photosynthetic Electron Transport ◽  
O2 Evolution ◽  
Blue Green Algae ◽  
High Concentrations

Thylakoid membrane preparations active in photosynthetic electron transport have been obtained from two marine red algae, Griffithsia monilis and Anotrichium tenue. High concentrations (0.5-1.0 M) of salts such as phosphate, citrate, succinate and tartrate stabilized functional binding of phycobilisomes to the membrane and also stabilized Photosystem II-catalysed electron-transport activity. High concentrations (1.0 M) of chloride and nitrate, or 30 mM-Tricine/NaOH buffer (pH 7.2) in the absence of salts, detached phycobilisomes and inhibited electron transport through Photosystem II. The O2-evolving system was identified as the electron-transport chain component that was inhibited under these conditions. Washing membranes with buffers containing 1.0-1.5 M-sorbitol and 5-50 mM concentrations of various salts removed the outer part of the phycobilisome but retained 30-70% of the allophycocyanin ‘core’ of the phycobilisome. These preparations were 30-70% active in O2 evolution compared with unwashed membranes. In the sensitivity of their O2-evolving apparatus to the composition of the medium in vitro, the red algae resembled blue-green algae and differed from other eukaryotic algae and higher plants. It is suggested that an environment of structured water may be essential for the functional integrity of Photosystem II in biliprotein-containing algae.

scholarly journals Plastocyanin is the long-range electron carrier between photosystem II and photosystem I in plants

2020 ◽  
Vol 117 (26) ◽  
pp. 15354-15362 ◽  
Author(s):  
Ricarda Höhner ◽  
Mathias Pribil ◽  
Miroslava Herbstová ◽  
Laura Susanna Lopez ◽  
Hans-Henning Kunz ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Long Range ◽  
Narrow Range ◽  
Higher Plants ◽  
Regulatory Element ◽  
Photosynthetic Electron Transport ◽  
Electron Carrier ◽  
Mobile Electron ◽  
Electron Carriers

In photosynthetic electron transport, large multiprotein complexes are connected by small diffusible electron carriers, the mobility of which is challenged by macromolecular crowding. For thylakoid membranes of higher plants, a long-standing question has been which of the two mobile electron carriers, plastoquinone or plastocyanin, mediates electron transport from stacked grana thylakoids where photosystem II (PSII) is localized to distant unstacked regions of the thylakoids that harbor PSI. Here, we confirm that plastocyanin is the long-range electron carrier by employing mutants with different grana diameters. Furthermore, our results explain why higher plants have a narrow range of grana diameters since a larger diffusion distance for plastocyanin would jeopardize the efficiency of electron transport. In the light of recent findings that the lumen of thylakoids, which forms the diffusion space of plastocyanin, undergoes dynamic swelling/shrinkage, this study demonstrates that plastocyanin diffusion is a crucial regulatory element of plant photosynthetic electron transport.

Glyphosate Does Not Inhibit Photosynthetic Electron Transport and Phosphorylation in Pea (Pisum sativum) Chloroplasts

Weed Science ◽  
1979 ◽  
Vol 27 (6) ◽  
pp. 684-688 ◽  
Author(s):  
E. P. Richard ◽  
J. R. Goss ◽  
C. J. Arntzen
Keyword(s):  
Electron Transport ◽  
Pisum Sativum ◽  
Photosynthetic Electron Transport ◽  
Photochemical Reactions ◽  
Transport Processes ◽  
Ps Ii ◽  
Dark Incubation ◽  
Fluorescence Studies ◽  
Mixture Prior

The activity of glyphosate [N-(phosphonomethyl)glycine], formulated as the isopropylamine salt, on in vitro photosynthesis was investigated. When pH 4.7 glyphosate solutions were titrated to a pH equal to that of the reaction media (pH 7.8), glyphosate additions had no effect on whole chain electron transport between coupled photosystem II (PS II) and photosystem I (PS I) in stroma-free chloroplast thylakoids from peas (Pisum sativumL. ‘Morse's Progress No. 9′). Inhibition did not occur even after a 2-h dark incubation of lamellae in a 5-mM solution of glyphosate. Fluorescence studies failed to detect an effect of glyphosate on PS-II mediated electron transport processes or upon light harvesting properties of PS II even after a 2-h glyphosate/chloroplast preincubation. Glyphosate had no effect on cyclic and noncyclic photophosphorylation even after a 100-min dark incubation of chloroplast membranes in a 5-mM solution of glyphosate. Based on these assays it is concluded that glyphosate has no direct effect on the photochemical reactions of photosynthesis when the pH of the active compound is adjusted to that of the reaction mixture prior to addition to a chloroplast suspension.

Mode of Inhibition of Photosynthetic Electron Transport by Substituted Diphenylethers

1981 ◽  
Vol 36 (9-10) ◽  
pp. 848-852 ◽  
Author(s):  
W. Draber ◽  
H. J. Knops ◽  
A. Trebst
Keyword(s):  
Electron Transport ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Thylakoid Membranes ◽  
Photosynthetic Electron Flow ◽  
Spinach Chloroplasts

Abstract Several substituted diphenylethers were found to be effective inhibitors of photosynthetic electron flow in isolated thylakoid membranes from spinach chloroplasts. T heir site of inhibition was localized with artificial acceptor and donor systems. The phenylether of an alkyl substituted nitrophenol is prim arely inhibiting electron flow after plastoquinone function whereas a dinitro-phenylether of a phenyl substituted nitrophenol is inhibiting before plastoquinone function. Therefore certain diphenylethers interfere with plastoquinone function at the oxidation or reduction site, depending on the substitution.

Mechanism of action of anions on the electron transport chain in thylakoid membranes of higher plants

2011 ◽  
Vol 43 (2) ◽  
pp. 195-202 ◽  
Author(s):  
Pooja Singh-Rawal ◽  
Ottó Zsiros ◽  
Sudhakar Bharti ◽  
Győző Garab ◽  
Anjana Jajoo
Keyword(s):  
Electron Transport ◽  
Mechanism Of Action ◽  
Electron Transport Chain ◽  
Higher Plants ◽  
Thylakoid Membranes ◽  
Transport Chain

A Phytotoxicity Biosensor using Photosynthetic Membranes

1990 ◽  
Vol 25 (2) ◽  
pp. 175-186 ◽  
Author(s):  
Marc Purcell ◽  
Robert Carpentier
Keyword(s):  
Electron Transport ◽  
Small Volume ◽  
Chlorophyll Concentration ◽  
Photosynthetic Electron Transport ◽  
Inhibitory Effect ◽  
Thylakoid Membranes ◽  
Photoelectrochemical Cell ◽  
Synthetic Membranes ◽  
Low Concentrations ◽  
Artificial Electron Acceptor

Abstract The potential of a photoelectrochemical cell employing photo-synthetic membranes in an application as a phytotoxicity biosensor is demonstrated. In this cell, a small volume (80 μl) of isolated thylakoid membranes is used to produce a photocurrent. The reduced species produced during photosynthetic electron transport are oxidized by soluble electroactive mediators which are reoxidized by a platinum working electrode. The photocurrent generated was inhibited by relatively low concentrations of herbicides, nitrite, sulfite and several heavy metals due to their inhibitory effect on photosynthetic electron transport. The cell sensitivity was enhanced when chlorophyll concentration was reduced and artificial electron acceptor concentration was increased.

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