title: Proton involvement with the light-induced hindrance of spin label motion in the lumen of spinach thylakoids.
abstract: The light-induced hindrance of spin label motion increases linearly with light intensity. However, it has not been possible to unambiguously demonstrate light saturation due to the very high rates of spin label reduction at high light intensity. The light-induced hindrance of spin label motion may be mimicked in the dark by subjecting thylakoids to appropriately low pH regimes. Uncouplers such as gramicidin-D and methylamine reduce the light-induced hindrance to dark levels as does ethylenedinitrilotetraacetate (EDTA) treatment. Valinomycin plus KCl which destroys the electric potential is only partially effective in reducing the light-induced hindrance. These results indicate that protons in the aqueous lumen of the thylakoids are closely involved with the observed light-induced hindrance of spin label motion.
mesh_terms: D002736:Chloroplasts / Q000378:metabolism* / Q000648:ultrastructure; D003497:Cyclic N-Oxides / Q000378:metabolism*; D004492:Edetic Acid / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D006096:Gramicidin / Q000494:pharmacology; D007425:Intracellular Membranes / Q000648:ultrastructure; D007700:Kinetics; D008027:Light; D008744:Methylamines / Q000494:pharmacology; D010084:Oxidation-Reduction; D011522:Protons; D013057:Spectrum Analysis; D013113:Spin Labels; D014475:Uncoupling Agents / Q000494:pharmacology; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D003497:Cyclic N-Oxides; D008744:Methylamines; D011522:Protons; D013113:Spin Labels; D014475:Uncoupling Agents; D006096:Gramicidin; C015527:4-amino-TEMPO; D014634:Valinomycin; D004492:Edetic Acid