Nuclear Magnetic Resonance Studies of the Structure of Model Membrane Systems: The Effect of Surface Curvature *

NMR Studies of Membrane Structure and Dynamics

“…Bloom et al (54), and Wennerstr6m & Ulmius (67) have, in fact, derived theoretical expressions for vesicle lineshapes. On the other hand, Chan and co-workers (17,18,44,68,69), and Horowitz et al (70) have argued that overall www.annualreviews.org/aronline Annual Reviews tumbling is too slow to produce the narrow resonances observed in vesicle spectra, and that the narrow lines occur as a result of additional disruption in the bilayer order caused by the extreme surface curvature in the vesicles. Finer's conclusions (66) were reached on the basis of a treatment of vesicle lineshapes that used the method of moments introduced by Gutowsky & Pake (71), and modified to meet the present situation.…”

Deuterium magnetic resonance: theory and application to lipid membranes

“…This demonstrates that the fluidity of a bilayer to a certain extent is independent of the order parameter and must be determined by a separate measurement. The necessary information could be provided by proton, carbon-13 or deuterium relaxation times (Horwitz et al 1973;Horwitz, Horsley & Klein, 1972;Metcalfe et al 1971;Metcalfe, Birdsall & Lee, 1973;Chan, Seiter & Feigenson, 1972;Chan et al 1973;Stockton et al 1976;Boden et al 1976). The interpretation of T x and T 2 relaxation times is however difficult since in an oriented system T x and T 2 depend upon the order ; A, spin label data (Hubbell & McConnell, 1971). as well as on the rate of motion.…”

Cholesterol reverts Triton X‐100 preferential solubilization of sphingomyelin over phosphatidylcholine: A 31P‐NMR study

“…This method is based on the fact that when lipids occur in large aggregates, e.g. multilamellar liposomes (MLV), the NMR line shape associated with the phosphoryl group is inhomogeneously broadened, because the magnetic dipolar interactions are not fully averaged spatially [19,20]. Nonetheless the much smaller lipid-detergent mixed micelles (Stokes radius 30-40 Å) tumble at a rate sufficiently fast to equalize magnetically all the molecules, thus cancelling the heterogeneity, and yielding narrow NMR signals [9,21,22].…”