Lateral diffusion rates of phosphatidylcholine in vesicle membranes: Eeffects of cholesterol and hydrocarbon phase transitions

Lipid polymorphism and the functional roles of lipids in biological membranes

“…In large bilayer structures, such as hand-shaken liposomes or biological membranes, the ability lipids to diffuse laterally does not produce an effective motional averaging mechanism as reorientation due to such processes is not fast on the NMR timescale (10 -s s). This is in contrast to the situation with small sonicated vesicles, where the lateral diffusion of the lipid around the vesicle and vesicle tumbling produce line-narrowing effects [43]. However, lipids in the hexagonal (Hn) phase do experience additional motional averaging as compared to those in large bilayer structures because motional averaging due to lateral diffusion around the small (-20 A diameter) aqueous channels occurs.…”

Further aspects of the Ca2+-dependent polymorphism of bovine heart cardiolipin

“…40). From the linewidth of the 31p-NMR signal it can be estimated [41] that the average radius of bilayer curvature is 180 ,~ assuming similar lateral diffusion rates of cardiolipin and egg phosphatidylcholine. The curbic phase is metastable as mechanical agitation immediately results in the formation of large bilayer vesicles.…”

31P-NMR studies on membrane phospholipids in microsomes, rat liver slices and intact perfused rat liver

“…The first two mechanisms are dependent on the size of the membrane system. The correlation time for isotropic motion of a lipid molecule in a spherical vesicle is related to the radius of the particle (a) and the rotational diffusion, D, according to [17] i _6 D…”