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European Journal of Biochemistry
BEN‐HAYYIM, G., Department of Botany, George S. Wise Center of Life Sciences, Tel-Aviv University, Ramat‐Aviv, Tel-Aviv, Israel
DRECHSLER, Z., Department of Botany, George S. Wise Center of Life Sciences, Tel-Aviv University, Ramat‐Aviv, Tel-Aviv, Israel
GOFFER, J., Department of Botany, George S. Wise Center of Life Sciences, Tel-Aviv University, Ramat‐Aviv, Tel-Aviv, Israel
NEUMANN, J., Department of Botany, George S. Wise Center of Life Sciences, Tel-Aviv University, Ramat‐Aviv, Tel-Aviv, Israel
3,3′‐Diaminobenzidine was shown to serve as an electron donor to photosystem 1 [in the presence of 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea. In Tris‐treated chloroplasts diaminobenzidine serves as an electron donor to photosystem 1 and to photosystem 2; the latter is sensitive to 3‐(3,4‐dichloro‐pheny 1)‐1,1‐dimethylurea. Addition of diaminobenzidine to Tris‐treated chloroplasts causes an increase in fluorescence yield. Diaminobenzidine‐dependent electron transport mediated by photosystem 2 is coupled to synthesis of ATP even in the absence of an electron acceptor. This phosphorylation which is presumably supported by cyclic electron flow, is sensitive to 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea. Diaminobenzidine‐dependent ATP formation, in Tris‐treated chloroplasts exhibits the red‐drop phenomenon. The diaminobenzidine‐induced cyclic photophosphorylation (mediated by photosystem 2) is resistant to a large extent to KCN‐treatment which is known to inhibit reactions catalyzed by photosystem 1.On the other hand ATP formation supported by electron transport from diaminobenzidine to methyl viologen in the presence of 3‐(3,4‐dichlorophenyl)‐1,1‐dirnethylurea] is largely inhibited by KCN‐treatment. This observation suggests that there are two coupling sites of ATP formation, one catalyzed by diaminobenzidine as a donor to photosystem 1 (in the presence of 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea), and the other supported by diaminobenzidine which acts both as a donor to photosystem 2 (in Tris‐treated chloroplasts) and as an acceptor (in its oxidized form) from a carrier located between the two photosystems. Copyright © 1975, Wiley Blackwell. All rights reserved
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Diaminobenzidine an Electron Donor to Photosystem 1 and to Photosystem 2 in Chloroplasts
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BEN‐HAYYIM, G., Department of Botany, George S. Wise Center of Life Sciences, Tel-Aviv University, Ramat‐Aviv, Tel-Aviv, Israel
DRECHSLER, Z., Department of Botany, George S. Wise Center of Life Sciences, Tel-Aviv University, Ramat‐Aviv, Tel-Aviv, Israel
GOFFER, J., Department of Botany, George S. Wise Center of Life Sciences, Tel-Aviv University, Ramat‐Aviv, Tel-Aviv, Israel
NEUMANN, J., Department of Botany, George S. Wise Center of Life Sciences, Tel-Aviv University, Ramat‐Aviv, Tel-Aviv, Israel
Diaminobenzidine an Electron Donor to Photosystem 1 and to Photosystem 2 in Chloroplasts
3,3′‐Diaminobenzidine was shown to serve as an electron donor to photosystem 1 [in the presence of 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea. In Tris‐treated chloroplasts diaminobenzidine serves as an electron donor to photosystem 1 and to photosystem 2; the latter is sensitive to 3‐(3,4‐dichloro‐pheny 1)‐1,1‐dimethylurea. Addition of diaminobenzidine to Tris‐treated chloroplasts causes an increase in fluorescence yield. Diaminobenzidine‐dependent electron transport mediated by photosystem 2 is coupled to synthesis of ATP even in the absence of an electron acceptor. This phosphorylation which is presumably supported by cyclic electron flow, is sensitive to 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea. Diaminobenzidine‐dependent ATP formation, in Tris‐treated chloroplasts exhibits the red‐drop phenomenon. The diaminobenzidine‐induced cyclic photophosphorylation (mediated by photosystem 2) is resistant to a large extent to KCN‐treatment which is known to inhibit reactions catalyzed by photosystem 1.On the other hand ATP formation supported by electron transport from diaminobenzidine to methyl viologen in the presence of 3‐(3,4‐dichlorophenyl)‐1,1‐dirnethylurea] is largely inhibited by KCN‐treatment. This observation suggests that there are two coupling sites of ATP formation, one catalyzed by diaminobenzidine as a donor to photosystem 1 (in the presence of 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea), and the other supported by diaminobenzidine which acts both as a donor to photosystem 2 (in Tris‐treated chloroplasts) and as an acceptor (in its oxidized form) from a carrier located between the two photosystems. Copyright © 1975, Wiley Blackwell. All rights reserved
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