Effect of different Fe(III) compounds on photosynthetic electron transport in spinach chloroplasts and on iron accumulation in maize plants

2008 ◽  
Vol 62 (4) ◽  
Author(s):  
Katarína Kráľová ◽  
Elena Masarovičová ◽  
František Šeršeň ◽  
Iveta Ondrejkovičová

AbstractSynthesis and spectral characteristics of [Fe(nia)3Cl3] and [Fe(nia)3(H2O)2](ClO4)3 are described. The effect of these compounds as well as of FeCl3·6H2O on photosynthetic electron transport in spinach chloroplasts was investigated using EPR spectroscopy. It was found that due to the interaction of these compounds with tyrosine radicals situated at the 161st position in D1 (TyrZ) and D2 (TyrD) proteins located at the donor side of photosystem (PS) II, electron transport between the photosynthetic centres PS II and PS I was interrupted. In addition, the treatment with [Fe(nia)3(H2O)2](ClO4)3 resulted in a release of Mn(II) from the oxygen evolving complex situated on the donor side of PS II. Moreover, the effect of the Fe(III) compounds studied on some production characteristics of hydroponically cultivated maize plants and on Fe accumulation in plant organs was investigated. In general, the production characteristic most inhibited by the presence of Fe(III) compounds was the leaf dry mass and [Fe(nia)3(H2O)2](ClO4)3 was found to be the most effective compound. The highest Fe amount was accumulated in the roots, and the leaves treated with Fe(III) compounds contained more Fe than the stems. The treatment with FeCl3·6H2O caused the most effective translocation of Fe into the shoots. Comparing the effect of nicotinamide complexes, [Fe(nia)3(H2O)2](ClO4)3 was found to facilitate the translocation of Fe into the shoots more effectively than [Fe(nia)3Cl3]. This could be connected with the different structure of these complexes. [Fe(nia)3(H2O)2](ClO4)3 has ionic structure and, in addition, coordinated H2O molecules can be easily substituted by other ligands.

1992 ◽  
Vol 47 (1-2) ◽  
pp. 63-68 ◽  
Author(s):  
Rekha Chaturvedi ◽  
M. Singh ◽  
P. V. Sane

Abstract The effect of exposure to strong white light on photosynthetic electron transport reactions of PS I and PS II were investigated in spinach thylakoids in the absence or presence of oxygen. Irrespective of the conditions used for photoinactivation, the damage to PS II was always much more than to PS I. Photoinactivation was severe under anaerobic conditions compared to that in air for the same duration. This shows that the presence of oxygen is required for prevention of photoinactivation of thylakoids. The susceptibility of water-splitting complex in photoinactivation is indicated by our data from experiments with chloride-deficient chloroplast membranes wherein it was observed that the whole chain electron transport from DPC to MV was much less photoinhibited than that from water. The data from the photoinactivation experiments with the Tris-treated thylakoids indicate another photodam age site at or near reaction centre of PS II. DCMU-protected PS II and oxygen-evolving complex from photoinactivation. DCMU protection can also be interpreted in terms of the stability of the PS II complex when it is in S2 state.


1980 ◽  
Vol 35 (3-4) ◽  
pp. 293-297 ◽  
Author(s):  
P. V. Sane ◽  
Udo Johanningmeier

Abstract Low concentrations (10 µM) of tetranitromethane inhibit noncyclic electron transport in spinach chloroplasts. A study of different partial electron transport reactions shows that tetranitromethane primarily interferes with the electron flow from water to PS II. At higher concentrations the oxidation of plastohydroquinone is also inhibited. Because diphenyl carbazide but not Mn2+ ions can donate electrons efficiently to PS II in the presence of tetranitromethane it is suggested that it blocks the donor side of PS II prior to donation of electrons by diphenyl carbazide. The pH dependence of the inhibition by this protein modifying reagent may indicate that a functional-SH group is essential for a protein, which mediates electron transport between the water splitting complex and the reaction center of PS II.


1979 ◽  
Vol 34 (11) ◽  
pp. 961-963 ◽  
Author(s):  
Klaus Bauer ◽  
Helmu Kodier

Abstract Short term effects of 2-(C-dichloro-acetylamino)-3-chloro-1,4-naphthoquinone (Hoe 13465, quinonamid*) and 2-amino-3-chloro-1,4-naphthoquinone (Hoe 17399, 06K-quinone) on cell suspensions of Chlorella vulgaris, Anabaena flos aquae, Porphyridium cruentum, and on isolated spinach chloroplasts were studied. The results clearly show that both substances inhibit the photosynthetic O2 production of algal suspensions as well as the electron transport of PS II in spinach chloroplasts. PS I is not inhibited by the action of the two algicides. At low concentrations quinonamid acts as a photosynthetic electron transport blocker, whereas Hoe 17399 is a weak inhibitor of photosynthetic electron flow. Mode of action of the two naphthoquinones is discussed. Both naphthoquinone derivatives can operate as an electron acceptor for PS I at low concentra­tions (10-5-10-6м). In addition there is observed a strong stimulation of dark respiration in algal cells induced by both of the compounds, Hoe 17399 causes a much higher stimulation rate than quinonamid does.


2012 ◽  
Vol 66 (8) ◽  
Author(s):  
Katarína Kráľová ◽  
František Šeršeň ◽  
Matúš Peško ◽  
Věra Klimešová ◽  
Karel Waisser

AbstractInhibition of photosynthetic electron transport (PET) in spinach chloroplasts by nineteen 2-benzylsulphanylbenzimidazoles (BZA) was studied. BZA were found to inhibit photosynthetic electron transport (PET) and for their inhibitory efficiency, electronic properties of the R substituent on the benzyl moiety are decisive. The PET inhibiting activity of the studied BZA expressed as IC50 varied in the range from 28.5 μM (R = 3,5-(CF3)2) to 394.5 μM (R = 2,4-(NO2)2). For compounds with R = H, 4-CH3, 3-CH3, 3-OCH3, 4-F, 3-F, 4-Cl, 3-Cl, 2-Cl, 4-Br, 3-Br, 3,4-F2, 3,4-Cl2, 3-CF3, 3,5-(CF3)2 linear increase of the inhibitory activity with the increasing value of the substituent’s σ constant up to 0.86 was observed. Further increase of the σ constant resulted in a sharp activity decrease of the corresponding compounds (R = 2-F-6-Cl, 2-NO2, 3,5-(NO2)2, 2,4-(NO2)2). Using EPR spectroscopy and an artificial electron donor diphenyl carbazide it was found that the site of BZA action in the photosynthetic apparatus is situated on the donor side of PS 2, prior to the Z·/D· intermediate.


1997 ◽  
Vol 62 (3) ◽  
pp. 516-520 ◽  
Author(s):  
Katarína Kráľová ◽  
František Šeršeň ◽  
Věra Klimešová ◽  
Karel Waisser

2-Alkylthio-4-pyridinecarbothiamides (1) inhibit photosynthetic electron transport in spinach chloroplasts. The dependence of photosynthesis-inhibiting activity upon the lipophilicity of 2-alkylthio substituent shows quasi-parabolic course with maximum effectiveness at 2-octyl derivative. The site of action of 1 is the intermediate D+, corresponding to tyrosine radical, which is situated in D2 protein on the donor side of photosystem 2.


1991 ◽  
Vol 46 (1-2) ◽  
pp. 93-98 ◽  
Author(s):  
Helen G. McFadden ◽  
Donald C. Craig ◽  
John L. Huppatz ◽  
John N. Phillips

Abstract X-ray crystallographic data for the highly potent cyanoacrylate photosynthetic electron transport inhibitor, (Z)-ethoxyethyl 3-(4-chlorobenzylamino)-2-cyano-4-methylpent-2-enoate, are presented. This compound has a particularly high affinity for the photosystem II (PS II) herbicide receptor with a p I50 value of 9.5 (in the Hill reaction under uncoupled condi­tions with a chlorophyll concentration of 0.1 μg/ml). Data regarding the structure of small li­gands, such as this potent cyanoacrylate, which bind to the site with high affinity may be used to provide the basis for modelling studies of PS II/herbicide complexes. The X-ray data presented confirm the Z-stereochemistry of active cyanoacrylates and demonstrate the pres­ence of a planar core stabilized by an intramolecular hydrogen bond between the ester car­bonyl oxygen and a benzylamino hydrogen atom. In order to assess the importance of the benzylamino -NH -group in this type of cyanoacrylate, analogues containing a methylene group in its place were synthesized and found to be 100-and 1000-fold less active as Hill inhibitors.


Weed Science ◽  
1979 ◽  
Vol 27 (6) ◽  
pp. 684-688 ◽  
Author(s):  
E. P. Richard ◽  
J. R. Goss ◽  
C. J. Arntzen

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.


1987 ◽  
Vol 891 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Magdolna Droppa ◽  
Jiři Masojidek ◽  
Zsuzsanna Rózsa ◽  
Adam Wolak ◽  
LászlóI. Horváth ◽  
...  

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