Multiparticle computer simulation of plastocyanin diffusion and interaction with cytochrome f in the electrostatic field of the thylakoid membrane

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.

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Binding of Antibodies onto the Thylakoid Membrane. V. Distribution of Proteins and Lipids in the Thylakoid Membrane

Zeitschrift für Naturforschung C ◽

10.1515/znc-1979-1219 ◽

1979 ◽

Vol 34 (12) ◽

pp. 1199-1204 ◽

Cited By ~ 6

Author(s):

Alfons Radunz

Keyword(s):

Thylakoid Membrane ◽

Major Part ◽

Membrane Surface ◽

Apparent Molecular Weight ◽

Average Diameter ◽

Cytochrome F ◽

Membrane Fragment ◽

Phosphatidyl Glycerol ◽

Lipid Mixture ◽

Monogalactosyl Diglyceride

Binding of antibodies to proteins and lipids onto fragments of the thylakoid membrane was studied and compared with the binding of antibodies by stroma-freed chloroplasts. The membrane fragments were prepared from stroma-free chloroplasts by ultrasonication and fractional centrifugation. The fragments have an average diameter of 200 A. Their thickness corresponds to that of the thylakoid membrane. The membrane fragments adsorb out of an antiserum to lipids approximately the same amount of antibodies as out of an antiserum to proteins. In comparison to this, stroma-free chloroplasts bind 4 times more antibodies to proteins than to lipids. From this it follows that the major part of the lipids is located in the membrane surface which is directed towards the inside or is located inside the membrane. As the chemical analysis has shown these results are not caused by an altered chemical composition of the membrane fragments. Despite the fact that membrane proteins bind considerably less protein antibodies than stroma-free chloroplasts, the antibody binding in membrane fragment might be considerably increased for certain proteins such as a polypeptide with an apparent molecular weight 24000 and cytochrome f. Antibodies to the major components of the lipid mixture, such as to monogalactosyl diglyceride, trigalactosyl diglyceride, sulfoquinovosyl diglyceride and phosphatidyl glycerol are 3 to 4 times more bound by membrane fragments than by stroma-free chloroplasts. From these results it is concluded that the thylakoid membrane surface directed towards the inside is preponderently composed of lipids whereas the surface directed towards the outside consists only by 10 to 15% of lipids.

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Binding of Antibodies onto the Thylakoid Membrane III. Proteins in the Outer Surface of the Thylakoid Membrane

Zeitschrift für Naturforschung C ◽

10.1515/znc-1978-9-1021 ◽

1978 ◽

Vol 33 (9-10) ◽

pp. 731-734 ◽

Cited By ~ 5

Author(s):

Alfons Radunz

Keyword(s):

Molecular Weight ◽

Electron Transport ◽

Outer Surface ◽

Thylakoid Membrane ◽

Apparent Molecular Weight ◽

Photosynthetic Electron Transport ◽

Coupling Factor ◽

Cytochrome F ◽

Threefold Increase ◽

Close Relationship

Abstract The maximal binding of antibodies to ferredoxin-NADP+ -reductase, cytochrome f, plastocyanin, coupling factor of photophosphorylation, carboxydismutase and to a polypeptide with the apparent molecular weight 24 000 onto stroma-freed chloroplasts of Antirrhinum majus was determined. The three proteins involved in photosynthetic electron transport bind approximately 0.05 to 0.07 g antibodies per g chloroplasts. The chloroplast preparation itself binds maximally about 1 gantibodies. From an antiserum to carboxydismutase and to a membrane polypeptide with the apparent molecular weight 24 000 approximately double the amount of antibodies namely 0.1 to 0.14 g antibodies per g chloroplasts are bound. Extraction of stroma-freed chloroplasts with 0.02 ᴍ Tris buffer pH 7.8 containing 0.7 mᴍ EDTA caused a threefold increase of the amount of bound anti bodies in the case of the membrane protein. 40% of the amount of antibodies which can be maximally bound by this chloroplast preparation is adsorbed out of an antiserum to the coupling factor.Out of an antiserum which contains equal concentrations of antibodies to ferredoxin-NADP+ -reductase, cytochrome f and plastocyanin the same amount of antibodies is bound as out of an antiserum directed to only one of these components. This shows that the proteins involved in electron transport are located in a very close relationship to each other in the outer surface of the thylakoid membrane.

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Studies of Components of the Thylakoid Membrane of Undamaged and Damaged Spruce Trees at Different Mountain Sites

Zeitschrift für Naturforschung C ◽

10.1515/znc-1993-11-1215 ◽

1993 ◽

Vol 48 (11-12) ◽

pp. 911-922 ◽

Cited By ~ 4

Author(s):

Aloysius Wild ◽

Petra Strobel ◽

Ute Flammersfeld

Keyword(s):

Electron Transport ◽

Photosystem Ii ◽

Chlorophyll Content ◽

Thylakoid Membrane ◽

Electron Transport Rate ◽

D1 Protein ◽

Cytochrome F ◽

West Germany ◽

Transport Rate ◽

Photosynthetic Membranes

During a five-year period, components of the thylakoid membrane in needles of the second generation of undamaged and damaged trees of Norway spruce were studied at three different mountain sites in West Germany. Visible signs of damage at these sites are a yellowing of the light-exposed sides of the needles as well as the loss of needles. The goal of this study was to determine damage-induced alterations in composition and physiological reactions of the thylakoid membranes in spruce needles. In order to meet this purpose, contents of chlorophyll a and b, electron transport rate of photosystem II, contents of the D 1 protein, cytochrome f, as well as P-700 were measured. The chlorophyll content in the needles of the damaged spruce trees was significantly lower than in the needles of the undamaged trees. In addition to this, the typical annual course of chlorophyll content was exclusively observed in the needles of the undamaged spruce trees. If related to dry weight, a drastic reduction of the electron transport rate and of the redox components of the thylakoid membrane was observed due to damage, indicating a degeneration of the photosynthetic membranes. The contents of D1 protein and the photosynthetic electron transport rates were also markedly reduced in the needles of the damaged trees, when related to chlorophyll content of thylakoids, suggesting an early and particular impairment of photosystem II. The comparison of spruce trees showing different signs of damage demonstrates that certain biochemical parameters concerning the photosynthetic membranes (chlorophyll, cytochrome f, ratio photosystem II/I) reflect the extent of damage and are suitable for an early indication of a beginning, but still invisible damage of spruce trees.

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Miltiparticle computer simulation of photosynthetic electron transport in the thylakoid membrane

BIOPHYSICS ◽

10.1134/s0006350907050053 ◽

2007 ◽

Vol 52 (5) ◽

pp. 481-488 ◽

Cited By ~ 5

Author(s):

I. B. Kovalenko ◽

A. M. Abaturova ◽

D. M. Ustinin ◽

G. Yu. Riznichenko ◽

E. A. Grachev ◽

...

Keyword(s):

Computer Simulation ◽

Electron Transport ◽

Thylakoid Membrane ◽

Photosynthetic Electron Transport

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Photosynthetic Responses of Pisum sativum to an Increase in Irradiance During Growth. II. Thylakoid Membrane Components

Functional Plant Biology ◽

10.1071/pp9870009 ◽

1987 ◽

Vol 14 (1) ◽

pp. 9 ◽

Cited By ~ 47

Author(s):

WS Chow ◽

JM Anderson

Keyword(s):

Thylakoid Membrane ◽

High Light ◽

Cytochrome F ◽

Reaction Centre ◽

Leaf Photosynthesis ◽

Low Light ◽

Ps Ii ◽

Reaction Centres ◽

Ps I ◽

Membrane Components

Following the transfer of pea plants grown at low irradiance (60 �mol photons m-2 s-1, 16 h light/8 h dark cycles) to high irradiance (390 �mol photons m-2 s-1), the extents and time courses of the increase in the concentrations of thylakoid membrane components on a chlorophyll basis have been determined. The increase in cytochrome f (~ 70%) and plastoquinone (~ 50%) contents occurred with no noticeable lag phase. The increase in photosystem Il reaction centres (PS II, ~ 35%) and ATP synthetase (~ 90%) occurred possibly with a lag period of 1-2 days. In contrast, there was no significant increase in the concentration of P700 (reaction centre) of PS I complex. The concentration of PS II reaction centres measured by atrazine-binding exceeded that from the O2 yield per single-turnover flash by a factor of 1.17 (compared with the expected value of 1.14); this contrasts with the factor of 1.8 obtained by P. A. Jursinic and R. Dennenberg [Arch. Biochem. Biophys. (1985) 241, 540-9]. It is suggested that both methods are equivalent for the determination of PS II reaction centres in active chloroplasts. The stoichiometry of PS II : cyt f: PS I was highly flexible, and not fixed at 1 : 1 : 1. We obtained the stoichiometries of 1.25 : 0.7 : 1.0 for low-light pea chloroplasts and 1.7 : 1.25 : 1.0 for chloroplasts in pea plants that had been transferred to high light for about 10 days, demonstrating the dynamic nature of thylakoid composition and function. In the first 2 days after transferring low light pea plants to high light, the time course of the increase in CO2- and light-saturated rate of leaf photosynthesis corresponded better with that of cyt f and plastoquinone than that of other chloroplast components examined. This suggests that, during the transition period, the relatively prompt increase of cyt b/f and plastoquinone plays a part in enhancing the CO2- and light-saturated rate of leaf photosynthesis.

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