title: Nuclear magnetic resonance description of molecular motion and phase separations of cholesterol in lecithin dispersions.
abstract: Proton-enhanced 13C nuclear magnetic resonance is used to obtain signals from labeled cholesterols in lecithin dispersions. The [26-(13)C]cholesterol resonance indicates that the aliphatic tail of the molecule undergoes reorientation fast enough to average completely the chemical shift anisotropy. In contrast, [4-(13)C]cholesterol signals are characteristic of limited anisotropic reorientation. The resonances from the 4 position are sensitive to the temperature-concentration phase diagram. A phase boundary is observed at about 20 mole percent cholesterol.
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002784:Cholesterol; D009682:Magnetic Resonance Spectroscopy; D008563:Membrane Lipids; D009038:Motion; D011663:Pulmonary Surfactants; D013696:Temperature
chemical_list: D008563:Membrane Lipids; D011663:Pulmonary Surfactants; D002784:Cholesterol