Plastoquinone compartmentation in chloroplasts. I. Evidence for domains with different rates of photo-reduction
The photo-reduction of plastoquinones by Photosystem II reaction centers was investigated using fluorescence and oxygen-evolution measurements in thylakoids deprived of Photosystem I acceptors. The process appears biphasic under limiting, as well as saturating, illumination. The 'fast' poo...
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E-Artikel |
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| Sprache: |
Englisch |
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1992 |
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Elsevier Journal Backfiles on ScienceDirect 1907 - 2002 |
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in: Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular - Amsterdam : Elsevier, 1101(1992), 1, Seite 1-12 |
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volume:1101 ; year:1992 ; number:1 ; pages:1-12 |
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NLEJ187712557 |
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| 245 | 1 | 0 | |a Plastoquinone compartmentation in chloroplasts. I. Evidence for domains with different rates of photo-reduction |
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| 520 | |a The photo-reduction of plastoquinones by Photosystem II reaction centers was investigated using fluorescence and oxygen-evolution measurements in thylakoids deprived of Photosystem I acceptors. The process appears biphasic under limiting, as well as saturating, illumination. The 'fast' pool fraction (about 6 PQ molecules per PS II center) represents 50-70% of the total. Its half reduction time under saturating light was found about 25-60 ms, while that of the 'slow' pool was 0.8-1 s. When the photo-reduction process is interrupted after reduction of the fast pool and resumed after a dark period, a redistribution of the reduced plastoquinones towards the slow pool is observed, with t"1"2 ~ 6 s. We interpret these results as expressing a limitation of PQ diffusion in the membrane and propose that the fast pool reflects the fraction present in the grana region where most PS II centers are located, while the slow pool corresponds to quinones from the stromal region. The relationship between the redox states of PQ and of the primary acceptor Q"A during photo-reduction of the fast pool expresses marked discrepancies with respect to a quasi-equilibrium relationship. This failure to achieve equilibrium on a rapid time-scale and the slow diffusion rate of quinones over long distances are accounted for by small size domains bounded by membrane proteins. In agreement with this view, we found that the amount of fast photo-reducible quinones is decreased when a fraction of PS II centers is inhibited, indicating that the domains contain, on average, about 3-4 PS II centers. We conclude that PQ cannot be responsible for the long range diffusion involved in rapid electron transfer from granal (PS II) to stromal (PS II) regions, a role that must be fulfilled by plastocyanin. | ||
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(DE-627)NLEJ187712557 (DE-599)GBVNLZ187712557 DE-627 ger DE-627 rakwb eng Plastoquinone compartmentation in chloroplasts. I. Evidence for domains with different rates of photo-reduction 1992 nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier The photo-reduction of plastoquinones by Photosystem II reaction centers was investigated using fluorescence and oxygen-evolution measurements in thylakoids deprived of Photosystem I acceptors. The process appears biphasic under limiting, as well as saturating, illumination. The 'fast' pool fraction (about 6 PQ molecules per PS II center) represents 50-70% of the total. Its half reduction time under saturating light was found about 25-60 ms, while that of the 'slow' pool was 0.8-1 s. When the photo-reduction process is interrupted after reduction of the fast pool and resumed after a dark period, a redistribution of the reduced plastoquinones towards the slow pool is observed, with t"1"2 ~ 6 s. We interpret these results as expressing a limitation of PQ diffusion in the membrane and propose that the fast pool reflects the fraction present in the grana region where most PS II centers are located, while the slow pool corresponds to quinones from the stromal region. The relationship between the redox states of PQ and of the primary acceptor Q"A during photo-reduction of the fast pool expresses marked discrepancies with respect to a quasi-equilibrium relationship. This failure to achieve equilibrium on a rapid time-scale and the slow diffusion rate of quinones over long distances are accounted for by small size domains bounded by membrane proteins. In agreement with this view, we found that the amount of fast photo-reducible quinones is decreased when a fraction of PS II centers is inhibited, indicating that the domains contain, on average, about 3-4 PS II centers. We conclude that PQ cannot be responsible for the long range diffusion involved in rapid electron transfer from granal (PS II) to stromal (PS II) regions, a role that must be fulfilled by plastocyanin. Elsevier Journal Backfiles on ScienceDirect 1907 - 2002 Joliot, P. oth Lavergne, J. oth Beal, D. oth in Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular Amsterdam : Elsevier 1101(1992), 1, Seite 1-12 (DE-627)NLEJ185338283 (DE-600)2209539-1 0167-4838 nnns volume:1101 year:1992 number:1 pages:1-12 http://dx.doi.org/10.1016/0167-4838(92)90460-U GBV_USEFLAG_H ZDB-1-SDJ GBV_NL_ARTICLE AR 1101 1992 1 1-12 |
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(DE-627)NLEJ187712557 (DE-599)GBVNLZ187712557 DE-627 ger DE-627 rakwb eng Plastoquinone compartmentation in chloroplasts. I. Evidence for domains with different rates of photo-reduction 1992 nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier The photo-reduction of plastoquinones by Photosystem II reaction centers was investigated using fluorescence and oxygen-evolution measurements in thylakoids deprived of Photosystem I acceptors. The process appears biphasic under limiting, as well as saturating, illumination. The 'fast' pool fraction (about 6 PQ molecules per PS II center) represents 50-70% of the total. Its half reduction time under saturating light was found about 25-60 ms, while that of the 'slow' pool was 0.8-1 s. When the photo-reduction process is interrupted after reduction of the fast pool and resumed after a dark period, a redistribution of the reduced plastoquinones towards the slow pool is observed, with t"1"2 ~ 6 s. We interpret these results as expressing a limitation of PQ diffusion in the membrane and propose that the fast pool reflects the fraction present in the grana region where most PS II centers are located, while the slow pool corresponds to quinones from the stromal region. The relationship between the redox states of PQ and of the primary acceptor Q"A during photo-reduction of the fast pool expresses marked discrepancies with respect to a quasi-equilibrium relationship. This failure to achieve equilibrium on a rapid time-scale and the slow diffusion rate of quinones over long distances are accounted for by small size domains bounded by membrane proteins. In agreement with this view, we found that the amount of fast photo-reducible quinones is decreased when a fraction of PS II centers is inhibited, indicating that the domains contain, on average, about 3-4 PS II centers. We conclude that PQ cannot be responsible for the long range diffusion involved in rapid electron transfer from granal (PS II) to stromal (PS II) regions, a role that must be fulfilled by plastocyanin. Elsevier Journal Backfiles on ScienceDirect 1907 - 2002 Joliot, P. oth Lavergne, J. oth Beal, D. oth in Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular Amsterdam : Elsevier 1101(1992), 1, Seite 1-12 (DE-627)NLEJ185338283 (DE-600)2209539-1 0167-4838 nnns volume:1101 year:1992 number:1 pages:1-12 http://dx.doi.org/10.1016/0167-4838(92)90460-U GBV_USEFLAG_H ZDB-1-SDJ GBV_NL_ARTICLE AR 1101 1992 1 1-12 |
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(DE-627)NLEJ187712557 (DE-599)GBVNLZ187712557 DE-627 ger DE-627 rakwb eng Plastoquinone compartmentation in chloroplasts. I. Evidence for domains with different rates of photo-reduction 1992 nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier The photo-reduction of plastoquinones by Photosystem II reaction centers was investigated using fluorescence and oxygen-evolution measurements in thylakoids deprived of Photosystem I acceptors. The process appears biphasic under limiting, as well as saturating, illumination. The 'fast' pool fraction (about 6 PQ molecules per PS II center) represents 50-70% of the total. Its half reduction time under saturating light was found about 25-60 ms, while that of the 'slow' pool was 0.8-1 s. When the photo-reduction process is interrupted after reduction of the fast pool and resumed after a dark period, a redistribution of the reduced plastoquinones towards the slow pool is observed, with t"1"2 ~ 6 s. We interpret these results as expressing a limitation of PQ diffusion in the membrane and propose that the fast pool reflects the fraction present in the grana region where most PS II centers are located, while the slow pool corresponds to quinones from the stromal region. The relationship between the redox states of PQ and of the primary acceptor Q"A during photo-reduction of the fast pool expresses marked discrepancies with respect to a quasi-equilibrium relationship. This failure to achieve equilibrium on a rapid time-scale and the slow diffusion rate of quinones over long distances are accounted for by small size domains bounded by membrane proteins. In agreement with this view, we found that the amount of fast photo-reducible quinones is decreased when a fraction of PS II centers is inhibited, indicating that the domains contain, on average, about 3-4 PS II centers. We conclude that PQ cannot be responsible for the long range diffusion involved in rapid electron transfer from granal (PS II) to stromal (PS II) regions, a role that must be fulfilled by plastocyanin. Elsevier Journal Backfiles on ScienceDirect 1907 - 2002 Joliot, P. oth Lavergne, J. oth Beal, D. oth in Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular Amsterdam : Elsevier 1101(1992), 1, Seite 1-12 (DE-627)NLEJ185338283 (DE-600)2209539-1 0167-4838 nnns volume:1101 year:1992 number:1 pages:1-12 http://dx.doi.org/10.1016/0167-4838(92)90460-U GBV_USEFLAG_H ZDB-1-SDJ GBV_NL_ARTICLE AR 1101 1992 1 1-12 |
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(DE-627)NLEJ187712557 (DE-599)GBVNLZ187712557 DE-627 ger DE-627 rakwb eng Plastoquinone compartmentation in chloroplasts. I. Evidence for domains with different rates of photo-reduction 1992 nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier The photo-reduction of plastoquinones by Photosystem II reaction centers was investigated using fluorescence and oxygen-evolution measurements in thylakoids deprived of Photosystem I acceptors. The process appears biphasic under limiting, as well as saturating, illumination. The 'fast' pool fraction (about 6 PQ molecules per PS II center) represents 50-70% of the total. Its half reduction time under saturating light was found about 25-60 ms, while that of the 'slow' pool was 0.8-1 s. When the photo-reduction process is interrupted after reduction of the fast pool and resumed after a dark period, a redistribution of the reduced plastoquinones towards the slow pool is observed, with t"1"2 ~ 6 s. We interpret these results as expressing a limitation of PQ diffusion in the membrane and propose that the fast pool reflects the fraction present in the grana region where most PS II centers are located, while the slow pool corresponds to quinones from the stromal region. The relationship between the redox states of PQ and of the primary acceptor Q"A during photo-reduction of the fast pool expresses marked discrepancies with respect to a quasi-equilibrium relationship. This failure to achieve equilibrium on a rapid time-scale and the slow diffusion rate of quinones over long distances are accounted for by small size domains bounded by membrane proteins. In agreement with this view, we found that the amount of fast photo-reducible quinones is decreased when a fraction of PS II centers is inhibited, indicating that the domains contain, on average, about 3-4 PS II centers. We conclude that PQ cannot be responsible for the long range diffusion involved in rapid electron transfer from granal (PS II) to stromal (PS II) regions, a role that must be fulfilled by plastocyanin. Elsevier Journal Backfiles on ScienceDirect 1907 - 2002 Joliot, P. oth Lavergne, J. oth Beal, D. oth in Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular Amsterdam : Elsevier 1101(1992), 1, Seite 1-12 (DE-627)NLEJ185338283 (DE-600)2209539-1 0167-4838 nnns volume:1101 year:1992 number:1 pages:1-12 http://dx.doi.org/10.1016/0167-4838(92)90460-U GBV_USEFLAG_H ZDB-1-SDJ GBV_NL_ARTICLE AR 1101 1992 1 1-12 |
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(DE-627)NLEJ187712557 (DE-599)GBVNLZ187712557 DE-627 ger DE-627 rakwb eng Plastoquinone compartmentation in chloroplasts. I. Evidence for domains with different rates of photo-reduction 1992 nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier The photo-reduction of plastoquinones by Photosystem II reaction centers was investigated using fluorescence and oxygen-evolution measurements in thylakoids deprived of Photosystem I acceptors. The process appears biphasic under limiting, as well as saturating, illumination. The 'fast' pool fraction (about 6 PQ molecules per PS II center) represents 50-70% of the total. Its half reduction time under saturating light was found about 25-60 ms, while that of the 'slow' pool was 0.8-1 s. When the photo-reduction process is interrupted after reduction of the fast pool and resumed after a dark period, a redistribution of the reduced plastoquinones towards the slow pool is observed, with t"1"2 ~ 6 s. We interpret these results as expressing a limitation of PQ diffusion in the membrane and propose that the fast pool reflects the fraction present in the grana region where most PS II centers are located, while the slow pool corresponds to quinones from the stromal region. The relationship between the redox states of PQ and of the primary acceptor Q"A during photo-reduction of the fast pool expresses marked discrepancies with respect to a quasi-equilibrium relationship. This failure to achieve equilibrium on a rapid time-scale and the slow diffusion rate of quinones over long distances are accounted for by small size domains bounded by membrane proteins. In agreement with this view, we found that the amount of fast photo-reducible quinones is decreased when a fraction of PS II centers is inhibited, indicating that the domains contain, on average, about 3-4 PS II centers. We conclude that PQ cannot be responsible for the long range diffusion involved in rapid electron transfer from granal (PS II) to stromal (PS II) regions, a role that must be fulfilled by plastocyanin. Elsevier Journal Backfiles on ScienceDirect 1907 - 2002 Joliot, P. oth Lavergne, J. oth Beal, D. oth in Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular Amsterdam : Elsevier 1101(1992), 1, Seite 1-12 (DE-627)NLEJ185338283 (DE-600)2209539-1 0167-4838 nnns volume:1101 year:1992 number:1 pages:1-12 http://dx.doi.org/10.1016/0167-4838(92)90460-U GBV_USEFLAG_H ZDB-1-SDJ GBV_NL_ARTICLE AR 1101 1992 1 1-12 |
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plastoquinone compartmentation in chloroplasts. i. evidence for domains with different rates of photo-reduction |
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Plastoquinone compartmentation in chloroplasts. I. Evidence for domains with different rates of photo-reduction |
| abstract |
The photo-reduction of plastoquinones by Photosystem II reaction centers was investigated using fluorescence and oxygen-evolution measurements in thylakoids deprived of Photosystem I acceptors. The process appears biphasic under limiting, as well as saturating, illumination. The 'fast' pool fraction (about 6 PQ molecules per PS II center) represents 50-70% of the total. Its half reduction time under saturating light was found about 25-60 ms, while that of the 'slow' pool was 0.8-1 s. When the photo-reduction process is interrupted after reduction of the fast pool and resumed after a dark period, a redistribution of the reduced plastoquinones towards the slow pool is observed, with t"1"2 ~ 6 s. We interpret these results as expressing a limitation of PQ diffusion in the membrane and propose that the fast pool reflects the fraction present in the grana region where most PS II centers are located, while the slow pool corresponds to quinones from the stromal region. The relationship between the redox states of PQ and of the primary acceptor Q"A during photo-reduction of the fast pool expresses marked discrepancies with respect to a quasi-equilibrium relationship. This failure to achieve equilibrium on a rapid time-scale and the slow diffusion rate of quinones over long distances are accounted for by small size domains bounded by membrane proteins. In agreement with this view, we found that the amount of fast photo-reducible quinones is decreased when a fraction of PS II centers is inhibited, indicating that the domains contain, on average, about 3-4 PS II centers. We conclude that PQ cannot be responsible for the long range diffusion involved in rapid electron transfer from granal (PS II) to stromal (PS II) regions, a role that must be fulfilled by plastocyanin. |
| abstractGer |
The photo-reduction of plastoquinones by Photosystem II reaction centers was investigated using fluorescence and oxygen-evolution measurements in thylakoids deprived of Photosystem I acceptors. The process appears biphasic under limiting, as well as saturating, illumination. The 'fast' pool fraction (about 6 PQ molecules per PS II center) represents 50-70% of the total. Its half reduction time under saturating light was found about 25-60 ms, while that of the 'slow' pool was 0.8-1 s. When the photo-reduction process is interrupted after reduction of the fast pool and resumed after a dark period, a redistribution of the reduced plastoquinones towards the slow pool is observed, with t"1"2 ~ 6 s. We interpret these results as expressing a limitation of PQ diffusion in the membrane and propose that the fast pool reflects the fraction present in the grana region where most PS II centers are located, while the slow pool corresponds to quinones from the stromal region. The relationship between the redox states of PQ and of the primary acceptor Q"A during photo-reduction of the fast pool expresses marked discrepancies with respect to a quasi-equilibrium relationship. This failure to achieve equilibrium on a rapid time-scale and the slow diffusion rate of quinones over long distances are accounted for by small size domains bounded by membrane proteins. In agreement with this view, we found that the amount of fast photo-reducible quinones is decreased when a fraction of PS II centers is inhibited, indicating that the domains contain, on average, about 3-4 PS II centers. We conclude that PQ cannot be responsible for the long range diffusion involved in rapid electron transfer from granal (PS II) to stromal (PS II) regions, a role that must be fulfilled by plastocyanin. |
| abstract_unstemmed |
The photo-reduction of plastoquinones by Photosystem II reaction centers was investigated using fluorescence and oxygen-evolution measurements in thylakoids deprived of Photosystem I acceptors. The process appears biphasic under limiting, as well as saturating, illumination. The 'fast' pool fraction (about 6 PQ molecules per PS II center) represents 50-70% of the total. Its half reduction time under saturating light was found about 25-60 ms, while that of the 'slow' pool was 0.8-1 s. When the photo-reduction process is interrupted after reduction of the fast pool and resumed after a dark period, a redistribution of the reduced plastoquinones towards the slow pool is observed, with t"1"2 ~ 6 s. We interpret these results as expressing a limitation of PQ diffusion in the membrane and propose that the fast pool reflects the fraction present in the grana region where most PS II centers are located, while the slow pool corresponds to quinones from the stromal region. The relationship between the redox states of PQ and of the primary acceptor Q"A during photo-reduction of the fast pool expresses marked discrepancies with respect to a quasi-equilibrium relationship. This failure to achieve equilibrium on a rapid time-scale and the slow diffusion rate of quinones over long distances are accounted for by small size domains bounded by membrane proteins. In agreement with this view, we found that the amount of fast photo-reducible quinones is decreased when a fraction of PS II centers is inhibited, indicating that the domains contain, on average, about 3-4 PS II centers. We conclude that PQ cannot be responsible for the long range diffusion involved in rapid electron transfer from granal (PS II) to stromal (PS II) regions, a role that must be fulfilled by plastocyanin. |
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Plastoquinone compartmentation in chloroplasts. I. Evidence for domains with different rates of photo-reduction |
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