Light adaptation of bacteriorhodopsin in the presence of valinomycin and potassium. pH-dependence |
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Authors: | Dominique Massotte Francois Boucher Jacques Aghion |
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Affiliation: | (1) Laboratoire de Biochimie, Département de Botanique (B22), Université de Liège, B-4000 Liège, Belgique;(2) Centre de recherche en photobiophysique, Université du Québec à Trois-Rivières, G9A 5H7 Trois-Rivières, Québec, Canada |
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Abstract: | In the presence of valinomycin and K+, bacteriorhodopsin undergoes (i) a decrease of its maximum absorbance, (ii) a blue shift of the maximum wavelength of both the light and the dark adapted forms. However (iii) a normal light adaptation is maintained and (iv) the retinal-retinal interactions are not perturbed. The role of valinomycin as a K+-carrier allowing a H+-K+ competition as well as the stabilization of the deprotonated Schiff-base (linking retinal to the apo-opsin) is shown and discussed.Abbreviations bR bacteriorhodopsin - CD circular dichroism - DA dark-adapted - LA light-adapted - M-412 Meta-intermediate of the bacteriorhodopsin photocycle |
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Keywords: | bacteriorhodopsin valinomycin purple membrane |
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