Energy-dependent changes in the ATP/ADP ratio at the tight nucleotide binding site of chloroplast ATP synthase |
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Authors: | Alexander N Malyan Heinrich Strotmann |
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Institution: | (1) Institute of Soil Science and Photosynthesis, Russian Academy of Science, 142292 Pushchino, Moscow Region, Russia;(2) Institut für Biochemie der Pflanzen, H. Heine Universität Dusseldorf, D-4000 Dusseldorf, Germany |
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Abstract: | Using DTT-modulated thylakoid membranes we studied tight nucleotide binding and ATP content in bound nucleotides and in the reaction mixture during 14C] ADP photophosphorylation. The increasing light intensity caused an increase in the rate of 14C] ADP incorporation and a decrease in the steady-state level of tightly bound nucleotides. Within the light intensity range from 11 to 710 w m–2, ATP content in bound nucleotides was larger than that in nucleotides of the reaction mixture; the most prominent difference was observed at low degrees of ADP phosphorylation. The increasing light intensity was accompanied by a significant increase of the relative ATP content in tightly bound nucleotides. The ratio between substrates and products formed at the tight nucleotide binding site during photophosphorylation was suggested to depend on the light-induced proton gradient across the thylakoid membrane.Abbreviations AdN
adenine nucleotide
- Chl
chlorophyll
- DTT
dithiothreitol
- FCCP
carbonylcianide p-trifluoromethoxyphenilhydrazone
- Pi
inorganic orthophosphate
- PMS
phenazine methosulfate
- TLC
thin-layer chromatography
- Tricine
N-tris(hydroxymethyl)methyl] glycine |
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Keywords: | ATP synthase chloroplast nucleotide binding photophosphorylation |
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