31P NMR first spectral moment study of the partial magnetic orientation of phospholipid membranes. |
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| Authors: | F Picard, M J Paquet, J Levesque, A B langer, M Auger |
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| Affiliation: | Département de Chimie, Centre de Recherche en Sciences et Ingénierie des Macromolécules, Université Laval, Québec, Québec G1K 7P4, Canada. |
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| Abstract: | Structural data can be obtained on proteins inserted in magnetically oriented phospholipid membranes such as bicelles, which are most often made of a mixture of long and short chain phosphatidylcholine. Possible shapes for these magnetically oriented membranes have been postulated in the literature, such as discoidal structures with a thickness of one bilayer and with the short acyl chain phosphatidylcholine on the edges. In the present paper, a geometrical study of these oriented structures is done to determine the validity of this model. The method used is based on the determination of the first spectral moment of solid-state (31)P nuclear magnetic resonance spectra. From this first moment, an order parameter is defined that allows a quantitative analysis of partially oriented spectra. The validity of this method is demonstrated in the present study for oriented samples made of DMPC, DMPC:DHPC, DMPC:DHPC:gramicidin A and adriamycin:cardiolipin. |
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