The marginal regions of thylakoid membranes: A partial characterization by polyoxyethylene sorbitan monolaurate (Tween 20) solubilization of spinach thylakoids |
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Authors: | Andrew N Webber Kathryn A Platt-Aloia Robert L Heath William W Thomson |
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Institution: | Dept of Botany and Plant Sciences, Univ. of California, Riverside, CA 92521, USA. |
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Abstract: | The detergent Tween-20 solubilized preferentially portions of the marginal regions of Spinacea oleracea L. thylakoid membranes and, thus, opened the inside of the grana to the external media. Differential centrifugation. following Tween-20 solubilization. enabled separate fractions of grana and stromal-exposed membranes to be isolated. Analysis of Tween-20 solubilized material, after pelleting all membrane material by centrifugation at 100 000 g, revealed polypeptides associated with the coupling factor (CF1) particles, cytochrome b6/f and photosystem II complexes, suggesting that the marginal membranes contain these proteins. Concomitantly, the 100 000 g pellet was depleted in cytochrome b6/f and P700, determined spectroscopically, Thus. our results reveal the margin to be a distinct membrane region, which does not contain the light-harvesting centers of photosystem II (LHC II). The implication of these results, in terms of the energetic interaction of components of granal and stromalexposed membrane regions, is discussed. |
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Keywords: | Chloroplast margins photochemical coupling Spinacea oleracea spinach thylakoids Tween 20 ultrastructure |
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