A 2H-NMR study of Acholeplasma laidlawii membranes highly enriched in myristic acid |
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Authors: | Harold C Jarrell Keith W Butler RAndrew Byrd Roxanne Deslauriers Irena Ekiel Ian CP Smith |
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Institution: | Division of Biological Sciences, National Research Council of Canada, Ottawa K1A 0R6 Canada |
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Abstract: | Myristic acid specifically deuterated at several positions along the acyl chain was biosynthetically incorporated into the membrane lipids of Acholeplasma laidlawii B to the level of ?90%. 2H-NMR was used to study the molecular order and lipid phase composition of the membranes as a function of temperature. Isolated membranes and intact cells give rise to similar 2H spectra. Below 25°C the spectra exhibit a broad gel phase component which at 0°C reaches the rigid limit value expected for an immobilized methylene group. Spectral moments were used to determine the relative amounts of gel and liquid crystalline phase lipids throughout the gel-liquid crystal phase transition. The results indicate that at the growth temperature (37 or 30°C) the A. laidlawii B membrane lipids are ~85–90% in the gel state, and that protein has little effect on lipid order of the liquid crystalline lipid, but leads to an increase in the linewidth by approx. 20%. |
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Keywords: | Phase transition Myristic acid Membrane structure (A laidlawii) |
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