scholarly journals Cyclic photophosphorylation and electron transport

1995 ◽  
Vol 1229 (1) ◽  
pp. 23-38 ◽  
Author(s):  
Derek S. Bendall ◽  
Robert S. Manasse
Keyword(s):  
Electron Transport ◽  
Cyclic Photophosphorylation

Localization and Function of Cytochrome f in the Thylakoid Membrane

1977 ◽  
Vol 32 (3-4) ◽  
pp. 271-280 ◽  
Author(s):  
Georg H. Schmid ◽  
Alfons Radunz ◽  
Wilhelm Menke
Keyword(s):  
Electron Transport ◽  
Outer Surface ◽  
Thylakoid Membrane ◽  
Time Lag ◽  
Photosynthetic Electron Transport ◽  
Cytochrome F ◽  
Antigenic Determinants ◽  
Light Reaction ◽  
Transport Reaction ◽  
Cyclic Photophosphorylation

Abstract A monospecific antiserum to cytochrome f agglutinates stroma-free swellable chloroplasts from tobacco and Antirrhinum. Consequently, antigenic determinants towards which the antiserum is directed are located in the outer surface of the thylakoid membrane. The antiserum inhibits linear photosynthetic electron transport. Just as described earlier for the antiserum to polypeptide 11000 this inhibition develops in the course of the light reaction. Ultrasonication in the presence of anti­ serum abolishes the light requirement and the maximal inhibition of the electron transport reaction is immediately observed. Electron transport in chloroplasts from a tobacco mutant which ex­ hibits only photosystem I-reactions is also inhibited by the antiserum. No time lag in the light for the onset of inhibition is observed with these chloroplasts. As chloroplasts of this mutant have only single unfolded thylakoids it appears that light might preponderantly open up partitions. If the light effect is interpreted in this way, cytochrome f should be located in the partition regions but nevertheless in the outer surface of the thylakoid membrane. However, a rearrangement of molecules in the membrane in the light by which the accessibility of cytochrome f is changed can­ not be excluded. The inhibition of linear electron transport by the antiserum is approximately 50 per cent and can only be increased to 75% upon the addition of antibodies to plastocyanin. The inhibition by the antiserum to cytochrome f as well as the combined inhibition by the antisera to cytochrome f and plastocyanin can be by-passed by DCPiP. It appears that cytochrome f and plastocyanin cannot be connected in series in the electron transport chain but are both closely associated in the thylakoid membrane. PMS-mediated cyclic photophosphorylation in chloroplasts from wild type tobacco and the tobacco mutant NC95 is only inhibited if the chloroplasts are sonicated in the presence of anti­ serum. If one disregards, that ultrasonication might cause reaction artifacts, it is thinkable that the cytochrome f, involved in the PMS-mediated cyclic photophosphorylation reaction, might be located inside the membrane.

Effects of 3,5-dibromo-4-hydroxybenzaldehyde O-(2,4-dinitrophenyl)oxime on Reactions of Mitochondria and Chloroplasts

Weed Science ◽  
1970 ◽  
Vol 18 (3) ◽  
pp. 419-426 ◽  
Author(s):  
D. E. Moreland ◽  
W. J. Blackmon
Keyword(s):  
Electron Transport ◽  
Oxygen Uptake ◽  
Electron Donor ◽  
Spinacia Oleracea ◽  
Herbicidal Activity ◽  
Oxygen Utilization ◽  
White Potato ◽  
Ferricyanide Reduction ◽  
Cyclic Photophosphorylation ◽  
Limited Oxygen

The effects of 3,5-dibromo-4-hydroxybenzaldehyde O-(2,4-dinitrophenyl)oxime (hereinafter referred to as C-9122), 3,5-dibromo-4-hydroxybenzonitrile (bromoxynil), 3,5-dibromo-4-hydroxybenzaldoxime (hereinafter referred to as bromoxime), and 2,4-dinitrophenol (hereinafter referred to as DNP) on phosphorylation and electron transport were measured in mitochondria isolated from white potato tubers (Solarium tuberosum L.) and in chloroplasts from spinach leaves (Spinacia oleracea L.). Mitochondrial oxygen utilization was monitored polarographically. All four chemicals stimulated ADP-limited oxygen utilization, inhibited non-ADP-limited oxygen uptake, and relieved oligomycin-inhibited oxygen uptake. C-9122 produced responses at lower molar concentrations than did bromoxynil, bromoxime, and DNP. The I50 value for inhibition of state 3 respiration by C-9122 was 2.7 × 10−6 M.In chloroplasts, C-9122, bromoxime, and DNP inhibited photoreduction and coupled photophosphorylation with water as the electron donor, and with ferricyanide and NADP as electron acceptors. Cyclic photophosphorylation, with phenazine methosulfate as the electron mediator under an argon gas phase, also was inhibited. With ascorbate-2,6-dichlorophenolindophenol (hereinafter referred to as DPIP) as the electron donor, phosphorylation coupled to NADP reduction was inhibited, but not the reduction of NADP. C-9122 was the strongest inhibitor, and bromoxime was the weakest inhibitor of the several reactions. The I50 value for inhibition of the coupled ferricyanide reduction was 4.6 × 10−6 M for C-9122. C-9122 appeared to act in two different ways by (a) inhibiting electron transport at or near photosystem II and the oxygen evolution pathway, and (b) interfering with energy transfer and the generation of ATP. Bromoxynil inhibited photoreduction and photophosphorylation reactions in which water served as the electron donor; but it was a very poor inhibitor of both cyclic photophosphorylation, and photophosphorylation coupled to NADP reduction with ascorbate-DPIP serving as the electron donor. Because of the pivotal role of ATP in cellular metabolism, it is conceivable that interference with ATP generation could be a major (but not necessarily the only) mechanism through which the herbicidal activity of C-9122 is expressed.

Mechanism of Action of the Herbicide 4,6-Dinitro-o-cresol in Photosynthesis

1979 ◽  
Vol 34 (11) ◽  
pp. 1021-1023 ◽  
Author(s):  
J. J. S. van Rensen ◽  
J. H. Hobé
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Mechanism Of Action ◽  
Chemical Structure ◽  
Methyl Viologen ◽  
Primary Electron ◽  
Reaction Centers ◽  
Mehler Reaction ◽  
Cyclic Photophosphorylation ◽  
Primary Electron Acceptor

Abstract The herbicide 4,6-dinitro-o-cresol inhibits electron transport to ferricyanide and non-cyclic photophosphorylation for 50% at about 15 μm. At higher concentrations the photosystem I depen­dent Mehler reaction ascorbate/dichlorophenolindophenol to methyl viologen is stimulated, while cyclic photophosphorylation is inhibited. The herbicide thus is an inhibitory uncoupler. Although the chemical structure of 4,6-dinitro-o-cresol is different from that of the diuron-type herbicides, its site and mechanism of action is similar. Both 4,6-dinitro-o-cresol and diuron inhibit electron transport between the primary electron acceptor of Photosystem II and the plastoquinone pool. This causes a closing of the reaction centers of Photosystem II. The interaction with the inhibited molecule however is different for the two herbicides.

The Effect of an Antiserum to Plastocyanin on Various Chloroplast Preparations

1975 ◽  
Vol 30 (3-4) ◽  
pp. 201-212 ◽  
Author(s):  
Georg Schmid ◽  
Alfons Radunz ◽  
Wilhelm Menke
Keyword(s):  
Electron Transport ◽  
Thylakoid Membrane ◽  
Electron Flow ◽  
Linear Electron ◽  
Wild Type ◽  
Lamellar System ◽  
Spinach Chloroplasts ◽  
Monospecific Antiserum ◽  
Cyclic Photophosphorylation ◽  
Aurea Mutant

Abstract A monospecific antiserum to tobacco plastocyanin agglutinates strom a-free sw ellable chloroplasts from wild type tobacco, (Nicotia na tabacum var. John William’s Broadleaf) from the tobacco aurea mutant Su/su2, (Nicotiana tabacum var. Su/su2) from Antirrhinum majus and spinach (Spi-nacia oleracea). In this condition the antiserum inhibits linear photosynthetic electron flow in tobacco and spinach chloroplasts. This inhibition of electron transport as well as the agglutination are not observed if the chloroplasts have been sonicated prior to antiserum addition. This is due to the fact that plastocyanin is removed by ultrasonication. The antiserum stimulates a number of photophosphorylation reactions in tobacco chloroplasts. This stimulation is always larger in the aurea mutant chloroplasts and in chloroplasts from yellow leaf patches of a variegated tobacco mutant (N . tabacum , var. NC95) than in the green type chloroplasts. The stimulation appears to be a consequence of the inhibition of linear electron transport. The antiserum does not affect PMS-mediated cyclic photophosphorylation in tobacco chloroplasts from the wild type whereas the reaction appears stimulated in the tobacco mutant chloroplasts. However, menadione-mediated cyclic photo­ phosphorylation is inhibited upon addition of the antiserum. The same is true for noncyclic photo­ phosphorylation coupled to electron transport in the aerobic system diaminodurene/ascorbate → methylviologen in the presence of N-tetraphenyl-p-phenylenediamine in spinach chloroplasts. If the lamellar system of Antirrhinum and spinach has lost its swellability neither agglutination nor inhibition of electron transport is observed. However, also in this state antibodies to plasto­ cyanin are specifically adsorbed onto the surface of the thylakoid membrane. This state which is characterized by a morphologically well preserved lamellar system is realized in chloroplast prepa­ rations from Antirrhinum and spinach and is termed stroma-freed, chloroplasts. In both states of the molecular structure of the thylakoid membrane, plastocyanin is located in the outer surface of the thylakoid. However, it cannot be excluded that functioning plastocyanin is also located in the interior of the thylakoid membrane.

Zum Mechanismus des photosynthetischen Elektronentransportes in isolierten Chloroplasten

1965 ◽  
Vol 20 (2) ◽  
pp. 143-147 ◽  
Author(s):  
Achim Trebst ◽  
Elfriede Pistorius
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
Phosphorylation Site ◽  
Atp Formation ◽  
Point Of Entry ◽  
Transport Chain ◽  
Endogenous Compounds ◽  
Cyclic Photophosphorylation ◽  
Photosynthetic Reactions ◽  
High Concentrations

The behavior of 2,3,5,6-tetramethyl-p-phenylendiamine (DAD) in photosynthetic reactions of isolated chloroplast fragments was compared with that of N-tetramethyl-p-phenylendiamine (TMPD). Both reverse the DCMU-inhibition of photosynthetic NADP-reduction. The DAD-system (at high concentrations of DAD), is coupled to a stoichiometric ATP-formation, whereas the TMPD-system is not. This shows that p-phenylendiamines, depending on their constitution, may react with components of the electron transport chain of chloroplasts before or after the phosphorylation site, and locates the phosphorylation step of photosynthetic phosphorylation between two endogenous compounds in that part of the electron transport chain, which connects the two light reactions of photosynthesis.At lower concentrations of DAD the diminished NADP-reduction is no longer coupled to ATP-formation, indicating a second point of entry of electrons from DAD into the electron transport chain. DAD, furthermore, is a cofactor of cyclic photophosphorylation. It therefore behaves like DCPIP, but the rates of the DAD-system are higher.

Polypeptides of the Thylakoid Membrane and Their Functional Characterization

1978 ◽  
Vol 33 (9-10) ◽  
pp. 723-730 ◽  
Author(s):  
Georg H. Schmid ◽  
Wilhelm Menke ◽  
Alfons Radunz ◽  
Friederike Koenig
Keyword(s):  
Molecular Weight ◽  
Electron Transport ◽  
Electron Donor ◽  
Photosystem I ◽  
Thylakoid Membrane ◽  
Apparent Molecular Weight ◽  
Variable Fluorescence ◽  
Phenazine Methosulfate ◽  
Cyclic Photophosphorylation ◽  
High Concentrations

Abstract From stroma-freed chloroplasts of Antirrhinum majus polypeptides with the apparent molecular weights 44 000, 26 000 and 20 000 were isolated.The antiserum to a polypeptide with the moleculair weight 44 000 inhibits the photoreduction of anthraquinone-2-sulfonate with dichlorophenol indophenol/ascorbate when the concentration of the electron donor dichlorophenol indophenol is low. The antiserum enhances the rate of phenazine methosulfate-mediated cyclic photophosphorylation. The variable fluorescence yield is increased by the antiserum . It is assumed that this polypeptide plays a role in electron transport between the two photosystems. From two polypeptides with the apparent molecular weight 26 000 one seems to belong to the reaction center of photosystem II as it inhibits the photooxidation of tetramethyl benzidine and diphenyl carbazide with suitable electron acceptors and inhibits electron transport between water and silicomolybdate. Variable fluorescence is not or not too strong decreased by the antiserum . The other polypeptide of the apparent molecular weight 26 000 inhibits the photoreduction of anthraquinone-2-sulfonate with high concentrations of dichlorophenol indophenol as the electron donor. Phenazine methosulfate-mediated cyclic photophosphorylation is also inhibited by the antiserum . Therefore, we should like to associate it with the reaction center of photosystem I. The antiserum to the polypeptide with the apparent molecular weight 20 000 inhibits the photoreduction of anthraquinone-2-sulfonate with low and high concentrations of the electron donor dichlorophenol indophenol. It enhances phenazine methosulfate-mediated cyclic photophosphorylation. The polypeptide, therefore, should be functionally involved on the acceptor side of photosystem I.The results obtained up-to-now on the function and localization of the polypeptides in the thylakoid membrane are summarized.

Response of Plant Tissues to Nitrofen

Weed Science ◽  
1971 ◽  
Vol 19 (6) ◽  
pp. 662-666 ◽  
Author(s):  
J. Francisco Pereira ◽  
Walter E. Splittstoesser ◽  
Herbert J. Hopen
Keyword(s):  
Electron Transport ◽  
Oxygen Uptake ◽  
Thermal Injury ◽  
Spinacia Oleracea ◽  
Stomatal Closure ◽  
Leaf Temperature ◽  
High Light ◽  
Plant Tissues ◽  
Cyclic Photophosphorylation ◽  
Germination And Growth

Nitrofen (2,4-dichlorophenylp-nitrophenyl ether) injured meristematic tissues and reduced germination and growth of cabbage (Brassica oleraceavar.capitataL.) in the dark. Cabbage was more susceptible to nitrofen when the plants were grown under a low water potential or when they were maintained in the dark after spraying. This toxicity was overcome by exogenous sucrose and light was not required for nitrofen activity. Nitrofen promoted membrane permeability of red beet (Beta vulgarisL.) root sections and this was enhanced by dimethylsulfoxide (DMSO). Sucrose or Carbowax 1500 prevented this increase in permeability. Nitrofen inhibited non-cyclic photophosphorylation and electron transport in isolated spinach (Spinacia oleraceaL.) chloroplasts and increased oxygen uptake of cabbage leaf sections. These effects appeared dependent upon permeability. Nitrofen induced stomatal closure, decreased transpiration, and increased leaf temperature. The leaf sustains thermal injury under high temperatures or high light intensities.

Regulatory electron transport pathways in cyclic photophosphorylation

FEBS Letters ◽  
1979 ◽  
Vol 102 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Daniel I. Arnon ◽  
Richard K. Chain
Keyword(s):  
Electron Transport ◽  
Transport Pathways ◽  
Cyclic Photophosphorylation

Quantitative Structure Activity Relationship of Diphenylamines as Inhibitors of Photosynthetic Electron Transport and Photophosphorylation

1979 ◽  
Vol 34 (11) ◽  
pp. 1024-1027 ◽  
Author(s):  
Walter Oettmeier
Keyword(s):  
Electron Transport ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Quantitative Structure Activity Relationship ◽  
Structure Activity Relationship ◽  
Activity Relationship ◽  
Quantitative Structure ◽  
Structure Activity ◽  
Cyclic Photophosphorylation ◽  
Relationship Of

Abstract A number of 16 substituted diphenylamines have been tested for their inhibitory activity on photosynthetic NADP reduction and photophosphorylation. The most active compounds exhibited pI50 values of 6.0 in photosynthetic electron transport and 6.8 in cyclic photophosphorylation, respectively. The inhibition site in electron flow of the diphenylamines is located between the two photosystems. Necessary for high activity is the substitution of the phenyl moieties by several strongly electron withdrawing substituents. A quantitative structure activity relationship according to a parabolic Hansch approach could be accomplished by using the Hammett electronic parameter as the only variable.

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