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פותח על ידי קלירמאש פתרונות בע"מ -
Proton Translocation and ATP Formation Coupled to Electron Transport from H2O to the Primary Acceptor of Photosystem 2
Year:
1977
Source of publication :
European Journal of Biochemistry
Authors :
בן חיים, גוזל
;
.
Volume :
72
Co-Authors:
BEN‐HAYYIM, G., Department of Botany, Tel-Aviv University, George S. Wise Center of Life Sciences, Ramat-Aviv, Tel-Aviv, Israel
NEUMANN, J., Department of Botany, Tel-Aviv University, George S. Wise Center of Life Sciences, Ramat-Aviv, Tel-Aviv, Israel
Facilitators :
From page:
57
To page:
61
(
Total pages:
5
)
Abstract:
The rate of electron transport from H2O to silicomolybdate in the presence of 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (diuron) (which involves the oxygen‐evolving enzyme, the photochemistry of photosystem 2 and the primary electron acceptor of photosystem 2) is controlled by internal pH. This is based on the shift of the pH profile of the rate of electron transport upon addition of uncouplers, or by using EDTA‐treated chloroplasts. Both stimulation and inhibition of electron transport by addition of uncouplers (depending on external pH) could be observed. These effects are obtained in the diuron‐insensitive photoreductions of either silicomolybdate or ferricyanide. These experiments provide strong evidence that a proton translocating site exists in the sequence of the electron transport H2O→ Q (the primary acceptor of photosystem 2). The photoreduction of silicomolybdate in the presence of diuron causes the formation of Δφ. The value of Δφ depends on the external pH and its maximal value was shown to be 2.4. The calculated internal pH at different external pH values was found to be rather constant, namely between 5.1‐5.2. Electron transport from H2O to silicomolybdate (in the presence of diuron) does not support ATP formation. It is suggested that this is due to the fact that the Δφ formed is below the “threshold”Δφ required for the synthesis of ATP. By adding an additional source of energy in the form of a dark diffusion potential created in the presence of K+ and valinomycin, significant amounts of ATP are formed in this system. Copyright © 1977, Wiley Blackwell. All rights reserved
Note:
Related Files :
adenosine triphosphate
Chloroplasts
Kinetics
plant
Plants
proton
Silicon
עוד תגיות
תוכן קשור
More details
DOI :
10.1111/j.1432-1033.1977.tb11224.x
Article number:
Affiliations:
Database:
סקופוס
Publication Type:
מאמר
;
.
Language:
אנגלית
Editors' remarks:
ID:
21675
Last updated date:
02/03/2022 17:27
Creation date:
16/04/2018 23:45
Scientific Publication
Proton Translocation and ATP Formation Coupled to Electron Transport from H2O to the Primary Acceptor of Photosystem 2
72
BEN‐HAYYIM, G., Department of Botany, Tel-Aviv University, George S. Wise Center of Life Sciences, Ramat-Aviv, Tel-Aviv, Israel
NEUMANN, J., Department of Botany, Tel-Aviv University, George S. Wise Center of Life Sciences, Ramat-Aviv, Tel-Aviv, Israel
Proton Translocation and ATP Formation Coupled to Electron Transport from H2O to the Primary Acceptor of Photosystem 2
The rate of electron transport from H2O to silicomolybdate in the presence of 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (diuron) (which involves the oxygen‐evolving enzyme, the photochemistry of photosystem 2 and the primary electron acceptor of photosystem 2) is controlled by internal pH. This is based on the shift of the pH profile of the rate of electron transport upon addition of uncouplers, or by using EDTA‐treated chloroplasts. Both stimulation and inhibition of electron transport by addition of uncouplers (depending on external pH) could be observed. These effects are obtained in the diuron‐insensitive photoreductions of either silicomolybdate or ferricyanide. These experiments provide strong evidence that a proton translocating site exists in the sequence of the electron transport H2O→ Q (the primary acceptor of photosystem 2). The photoreduction of silicomolybdate in the presence of diuron causes the formation of Δφ. The value of Δφ depends on the external pH and its maximal value was shown to be 2.4. The calculated internal pH at different external pH values was found to be rather constant, namely between 5.1‐5.2. Electron transport from H2O to silicomolybdate (in the presence of diuron) does not support ATP formation. It is suggested that this is due to the fact that the Δφ formed is below the “threshold”Δφ required for the synthesis of ATP. By adding an additional source of energy in the form of a dark diffusion potential created in the presence of K+ and valinomycin, significant amounts of ATP are formed in this system. Copyright © 1977, Wiley Blackwell. All rights reserved
Scientific Publication
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