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ABSTRACT: The electron paramagnetic resonance method was used to study the interactions of amaranthin with isolated class B chloroplasts from broad bean (Vicia faba L.) and amaranth (Amaranthus tricolor L.) during the light-driven electron and proton transport. Amaranthin was shown to interact with electron transport chain of chloroplasts at the PS II level; it also affects the electron transport near PS I. At the same time, amaranthin had no significant inhibitory effect on the light-dependent formation of the transmembrane pH gradient.
Russian Journal of Plant Physiology 08/2002; 49(5):585-591. · 0.71 Impact Factor
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Doklady Akademii nauk SSSR 02/1987; 296(2):470-4.
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ABSTRACT: The effects of two molecular forms of water-soluble ferredoxin (Fd I and Fd II) on the kinetics of electron transport in bean chloroplasts (class B) were studied. The light-induced redox transitions of the photosystem I reaction center P700 were measured by the intensity of the EPR signal I produced by P700+. Both forms of ferredoxin, Fd I and Fd II, when added to the chloroplasts in catalytic amounts, stimulate the light-induced electron transfer from P700 to NADP+. Nevertheless, Fd I is a better mediator of the back reactions from NADPH to P700+. This electron transfer pathway is sensitive to the cyclic electron transport inhibitor, antimycin A, and to DCMU inhibitor of electron transport between photosystem II and plastoquinone. It may be concluded that the two molecular forms of ferredoxin, Fd I and Fd II, differ in their ability to catalyze cyclic electron transport in photosystem I. The role of Fd I and Fd II in regulation of electron transport at the acceptor site of photosystem I is discussed.
Biokhimii͡a (Moscow, Russia) 12/1982; 47(11):1859-66.
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ABSTRACT: The reactivities of the SH-groups of pea and corn ferredoxins were found to be different. One or two SH-groups in the molecule of pea ferredoxin and one SH-group in the molecule of corn ferredoxin are readily available for the thyol group specific reagents. Four SH-groups of both ferredoxins are completely masked, i. e. available for the thyol reagents only after protein denaturation in the presence of urea. The rates of SH-group interaction with the sulfhydryl reagents in corn ferredoxin are lower than those in pea ferredoxin. The non-haem iron of pea ferredoxin interacts with the complex formers far more rapidly as compared to corn ferredoxin. The ferredoxins tested differ in the amount of iron atoms. The latter require the presence of oxygen for their complete interaction with the complex formers.
Biokhimii͡a (Moscow, Russia) 08/1979; 44(7):1184-91.
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Biokhimii͡a (Moscow, Russia) 37(5):1012-8.
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ABSTRACT: The reduction of iron-sulphur protein of the higher plant ferrodoxin has been studied by polarographical methods. Ferredoxin initiates a reversible wave with E1/2=--0,61 v (N. C. E.) at pH 7. Protein absorption greatly influences the electrochemical reduction. The protons have been shown to take part in the electrode reaction. The potentiometrically obtained data about the difference between E1/2 and E0=--0.70 v and its causative factors are discussed. As a result of the experiments with modification of ferredoxin active centre it has been concluded that the active centre participates in the polarographical reduction.
Biofizika 21(1):35-9. · 0.43 Impact Factor
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ABSTRACT: A comparison of plastocyanin isolated from pea and corn leaves was made according to a number of indices. No appreciable differences were detected between the proteins in molecular weight or sedimentation constants. In addition, it was shown that plastocyanin of corn, in comparison with the pea protein, possesses greater thermal stability, is more resistant to the action of high and low H+ ion concentrations, as well as to the action of concentrated solutions of urea and guanidine nitrate. The detected differences indicate peculiarities in the molecular organization of plastocyanins from various groups of plants. It is suggested that the differences noted in the structure of plastocyanins can ensure effective functioning of proteins under nonuniform conditions of the external environment.
Biology bulletin of the Academy of Sciences of the USSR 5(3):305-9.
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ABSTRACT: In the experiments with reaction center modification of ferredoxin its participation in reduction has been shown. Polarographic characteristics of ferredoxin and apoferredoxin have been compared. While removing iron and labile sulphur from ferredoxin reaction center the reduction wave of Fe-S bonds with E 1/2 = -0.33 V (N. H. E.) transforms into the reduction wave of S-S bonds with E 1/2 = -0,39 V at pH = 7.
Biofizika 26(1):129-30. · 0.43 Impact Factor
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ABSTRACT: It was shown that the temperature optimum of the activity in NADP photoreduction by isolated chloroplasts could be significantly different for ferredoxins prepared from various photosynthetic organisms. Thus, maize ferredoxin was found to display maximum activity at temperatures higher than those of pea ferredoxin. Maize ferredoxin was also more heat-stable than pea protein, especially in the presence of oxygen.
Plant Science Letters 2(2):115-118.
