Interaction of Photosystem II Herbicides with Bicarbonate and Formate in Their Effects on Photosynthetic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 374-377 ◽  
Author(s):  
J. J. S. van Rensen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Amaranthus Hybridus ◽  
Apparent Affinity ◽  
Photosynthetic Electron Flow ◽  
Different Characteristics ◽  
The Hill

The reactivation of the Hill reaction in CO2-depleted broken chloroplasts by various concentrations of bicarbonate was measured in the absence and in the presence of photosystem II herbicides. It appears that these herbicides decrease the apparent affinity of the thylakoid membrane for bicarbonate. Different characteristics of bicarbonate binding were observed in chloroplasts of triazine-resistant Amaranthus hybridus compared to the triazine-sensitive biotype. It is concluded that photosystem II herbicides, bicarbonate and formate interact with each other in their binding to the Qв-protein and their interference with photosynthetic electron transport.

On a new inhibitor of photosynthetic electron-transport in isolated chloroplasts

1970 ◽  
Vol 25 (10) ◽  
pp. 1157-1159 ◽  
Author(s):  
A. Trebst ◽  
E. Harth ◽  
W. Draber
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
High Concentration ◽  
Ferricyanide Reduction ◽  
The Hill ◽  
Photosystem I And Ii ◽  
Isolated Chloroplasts

A halogenated benzoquinone has been found to inhibit the photosynthetic electron transport system in isolated chloroplasts. 2·10-6ᴍ of dibromo-thymoquinone inhibit the Hill- reaction with NADP, methylviologen or anthraquinone to 100%, but do not effect the photoreduction of NADP at the expense of an artificial electron donor. The Hill - reaction with ferricyanide is inhibited even at the high concentration of 2·10-5ᴍ of dibromo-thymoquinone to only 60%. The remaining reduction in the presence of the inhibitor reflects the rate of ferricyanide reduction by photosystem II. It is concluded that the inhibition of electron transport by the quinone occurs between photosystem I and II and close to or at the functional site of plastoquinone.

Site of Action of 2,5-Dimethoxy-3,6-Dichloro-p-Benzoquinone in the Photosynthetic Electron Transport Chain

1981 ◽  
Vol 36 (7-8) ◽  
pp. 656-661 ◽  
Author(s):  
G. Sarojini ◽  
H. Daniell
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Transport Chain ◽  
Electron Transport Rate ◽  
Electron Flow ◽  
Electron Acceptors ◽  
Hill Reaction ◽  
Transport Chain ◽  
Site Of Action ◽  
The Hill

Abstract Electron Acceptors, Photosystem II, Quinones and Quinonediamines Dichlorodimethoxy-/?-benzoquinone (DCDMQ) was tested for its site of action in the photo­ synthetic electron transport chain. Hill reaction mediated by DCDMQ was insensitive to DBMIB (1 nm) but sensitive to DCMU, suggesting its site of action before plastoquinone but after Q -the primary electron acceptor of photosystem II. Extraction of freeze-dried chloroplasts with heptane and analyzing their capacity to photo-oxidize water using various Hill oxidants revealed that silicomolybdate (SiMO) and DCDMQ could effectively restore the activity. Diaminodurene (DAD) in the presence of ferricyanide could restore 40% of the activity. But ferricyanide alone failed to restore the ability to photo-oxidize water in heptane extracted chloroplasts. Similarly, N a2S 0 3 which is known to cause a bottleneck in the electron flow at plastoquinone affected the ferricyanide Hill reaction. Hill reactions mediated by SiMO and DCDMQ were insensitive to the addition of Na2SO3, suggesting that both these oxidants intercept electrons before plastoquinone. But 50% of the activity was lost when sulfite was added to the Hill reaction mediated by DADox. DNP-INT, melittin and picrylhydrazyl were recently introduced as photosystem II inhibitors inhibiting the electron flow between Q and the PQ pool. While DCBQ and DCDMQ Hill reactions were insensitive to DNP-INT, ferricyanide was highly sensitive. The quinonediamines TMPD and DADox showed 50% decrease in the electron transport rate, similar to heptane extracted or sulfite inhibited chloroplasts. Melittin increased the electron transport rate when ferricyanide or TMPD was the Hill oxidant, while DCBQ and DCDMQ reduction remained unaffected. However, DADox Hill reaction showed 50% inhibition in the presence of melittin. Picrylhydrazyl - which inhibits the electron flow between Q and the PQ pool - inhibited the Hill reaction of all the PS II electron acceptors except that of DCDMQ. It is possible that there is another site of intercepting electrons between Q and plastoquinone before the site where most of the quinonediamines accept electrons.

Effect of an Antiserum to a Thylakoid Membrane Polypeptide on the Primary Photoreaction of Photosystem II

1976 ◽  
Vol 31 (9-10) ◽  
pp. 594-600 ◽  
Author(s):  
Georg H. Schmid ◽  
Gernot Renger ◽  
Michael Gläser ◽  
Friederike Koenig ◽  
Alfons Radunz ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Flow ◽  
Primary Electron ◽  
Hill Reaction ◽  
Ps Ii ◽  
Absorption Change ◽  
Oxygen Evolving ◽  
The Hill

Abstract As was described previously, an antiserum to polypeptide 11000 inhibited photosynthetic elec­tron transport on the oxygen evolving side of photosystem II. The effect of the antiserum on chloro­plasts from two tobacco mutants also clearly showed that the inhibition site is on the photosystem II-side of the electron transport chain. One of the two tobacco mutants lades the oxygen evolving capacity but exhibits some electron transport with tetramethyl benzidine, an artificial donor to PS II. In this mutant electron transport was barely inhibited. The effect of the antiserum on the primary photoevents showed that the initial amplitude of the absorption change of chlorophyll an at 690 nm and that of the primary electron acceptor X320 at 334 nm both diminished in the presence of the antiserum. Both signals were restored upon addition of diphenylcarbazide another artificial donor to photosystem II. Comparison of the degree of inhibition on the amplitudes of the fast and slow components of the 690 nm absorption change with the manometrically measured inhibition of electron transport shows that besides a full inactivation of a part of the reaction centers of photosystem II another part apparently mediates a fast cyclic electron flow around photosystem II as reported by Renger and Wolff earlier for tris-treated chloroplasts. Moreover, the antiserum affects the low temperature fluorescence in a way which is opposite to Murata’s effect of the Mg2+ -ion induced inhibition of energy spill-over from photosystem II to photosystem I. The antiserum under the condition in which the Hill reaction is inhibited lowered the 686 nm emission and enhanced the 732 nm emission which indicates an enhanced energy spill-over to photosystem I.

Reactions of Antisera to Lutein and Plastoquinone with Chloroplast Preparations and their Effects on Photosynthetic Electron Transport

1973 ◽  
Vol 28 (1-2) ◽  
pp. 36-44 ◽  
Author(s):  
Alfons Radunz ◽  
Georg H. Schmid
Keyword(s):  
Electron Transport ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Potassium Ferricyanide ◽  
Electron Donors ◽  
Hill Reaction ◽  
Photosynthetic Electron Transport Chain ◽  
Transport Chain ◽  
Pass Through ◽  
The Hill

An antiserum to lutein inhibits photosynthetic electron transport between water and potassium ferricyanide in diloroplasts from green Nicotiana tabacum var. John William’s Breadleaf. However, electron transport between diphenylcarbazide and potassium ferricyanide is not impaired. From this it is concluded that the photochemically active carotenoid should feed its electrons into the photosynthetic electron transport chain before the site from which diphenyl-carbazide donates electrons. The inhibition of the ferricyanide Hill reaction in diloroplasts by antibodies to lutein depends on the accessibility of the carotenoid antigen in the thylakoid membrane. In fresh preparations the accessibility is greater in diloroplasts in which photo- synthetic electron transport is coupled to photophosphorylation. Concomitantly the antiserum to lutein agglutinates only such chloroplast preparations in which the Hill reaction is impaired by the antiserum. An antiserum to plastoquinone inhibits ferricyanide photoreduction of diloroplasts regardless whether driven by water or diphenylcarbazide as the electron donors. Typical photosystem-I-reactions are not influenced by the antiserum. In a certain type of chloroplast preparations the antiserum does not inhibit PMS-mediated photophosphorylation inferring that plastoquinone, eventually involved in this reaction, is either not accessible to antibodies, or that this cyclic electron flow does not necessarily pass through plastoquinone.

Pentachlorophenol Inhibits Photosynthetic Electron Flow and Quenches Chlorophyll Fluorescence after Preillumination

1986 ◽  
Vol 41 (4) ◽  
pp. 433-436 ◽  
Author(s):  
Christof Niehrs ◽  
Jan Ahlers
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Electron Flow ◽  
Hill Reaction ◽  
Light Requirement ◽  
Ps Ii ◽  
Photosynthetic Electron Flow ◽  
Fluorescence Quench ◽  
The Common ◽  
The Hill

The pesticide PCP was shown to inhibit the Hill reaction in broken chloroplasts (I50 = 15 μᴍ) and to quench chlorophyll fluorescence. Both effects require preillumination. In contrast to the common “phenol-type” inhibitors, neither inhibition of Hill reaction nor chlorophyll fluorescence quench were affected by pretreatment of chloroplast with trypsin instead of preillumination. An inhibition site differing from the “phenol type” inhibitors is therefore assumed. The results presented indicate that the observed light requirement is due to electron transport through PS II. Measurements of intrinsic tryptophane fluorescence relate the PCP site of binding to a hydro- phobic environment.

Formate as an Inhibitor of Photosynthetic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 386-388 ◽  
Author(s):  
Jan F. H. Snel ◽  
Dirk Naber ◽  
Jack J. S. van Rensen
Keyword(s):  
Inhibitory Action ◽  
Electron Flow ◽  
Hill Reaction ◽  
Maximal Inhibition ◽  
Photosynthetic Electron Flow ◽  
The Hill

The effects of formate on the Hill reaction in isolated broken pea chloroplasts were in­vestigated. Addition of formate to chloroplasts has two distinct effects: I. basal electron flow can be stimulated 3-fold; 2. uncoupled electron flow is inhibited. The stimulating effect is due to uncoupling by formate and appears instantaneous. Maximal inhibition by form ate is only observed after prolonged illumination. The inhibitory action of form ate on electron flow can be relieved by bicarbonate *.

X-Ray Structure Analysis of a Cyanoacrylate Inhibitor of Photosystem II Electron Transport

1991 ◽  
Vol 46 (1-2) ◽  
pp. 93-98 ◽  
Author(s):  
Helen G. McFadden ◽  
Donald C. Craig ◽  
John L. Huppatz ◽  
John N. Phillips
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll Concentration ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Ps Ii ◽  
X Ray ◽  
High Affinity ◽  
Modelling Studies ◽  
Intramolecular Hydrogen

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.

Inhibition by Tetranitromethane of Photosynthetic Electron Transport from Water to Photosystem II in Chloroplasts

1980 ◽  
Vol 35 (3-4) ◽  
pp. 293-297 ◽  
Author(s):  
P. V. Sane ◽  
Udo Johanningmeier
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Ph Dependence ◽  
Photosynthetic Electron Transport ◽  
Donor Side ◽  
Ps Ii ◽  
Diphenyl Carbazide ◽  
Low Concentrations ◽  
Sh Group

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.

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.

Photoautotrophic Cultured Plant Cells: A Novel System to Survey New Photosynthetic Electron Transport Inhibitors

1991 ◽  
Vol 46 (7-8) ◽  
pp. 563-568 ◽  
Author(s):  
Fumihiko Sato ◽  
Yasuyuki Yamada ◽  
Sang Soo Kwak ◽  
Katsunori Ichinose ◽  
Mitsuhiro Kishida ◽  
...  
Keyword(s):  
Electron Transport ◽  
Cultured Cells ◽  
Plant Cells ◽  
Photosynthetic Electron Transport ◽  
Herbicidal Activity ◽  
Marchantia Polymorpha ◽  
Hill Reaction ◽  
Transport Inhibitors ◽  
Comparison Of The Results ◽  
The Hill

Abstract The responses of photoautotrophic (PA) cultured cells of tobacco (Nicotiana tabacum cv. Samsun NN) and liverwort (Marchantia polymorpha L.) to thirty-eight cyclohexanedione derivatives were surveyed. Each derivative was also tested for inhibitory activity on photosynthetic electron transport (PET), using isolated thylakoids, and herbicidal activity, using seed­ lings and mature plants. Comparison of the results from the different assays showed that the responses of PA cells to each com pound correlated more closely with the responses of seed­ lings and mature plants than did the results of the Hill reaction assays. Our findings suggest that PA cultured cells would be a suitable screening material for identifying potential herbicides with PET-inhibiting activity.

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