EFFECT OF CHOLESTEROL IN MEMBRANES - PULSED NUCLEAR MAGNETIC-RESONANCE MEASUREMENTS OF LIPID LATERAL DIFFUSION

Lateral diffusion coefficients of lipids in a bilayer can be measured directly in a macroscopically aligned sample by use of a pulsed NMR method with pulsed magnetic field gradients. This technique was utilized to investigate the influence of cholesterol on the lipid diffusion of egg yolk lecithin, palmitoyloleoyllecithin and dioleoyllecithin. Cholesterol has a very small effect on the phospholipid diffusion. Cholesterol has a great influence on the molecular ordering in the bilayer and on the lipid phase structure. Cholesterol probably exerts its dominant effect on the lipid membrane stability.