Deuterium magnetic resonance study of cholesteryl esters in membranes.
The ternary systems EYL:H2O (50:50 wt %) containing 1 and 5 mol % cholesteryl palmitate-d31 or 1 and 5 mol % cholesteryl palmitate-16,16,16,16-d3 have been studied. Cholesteryl palmitate-d31 gave a unique deuterium magnetic resonance spectrum corresponding to a homogeneous (delta vQ = 3 and 12 kHz) and a solid phase (deltaVQ = 38 and 118 kHz). From the characteristic spectra and spin-lattice relaxation times, a procedure for calculating the amount of each phase present in the ternary mixture is given resulting in a maximum value of homogeneously dissolved cholesteryl palmitate of 0.2 +/- 0.1 mol % and a solid fraction above 0.2 mol %. The most probable order parameter for the (-CD2)n portion of the homogeneous fraction of cholesteryl palmitate-d31 was determined from the quadrupolar splittings to be S = 0.1 which is less than one-half that of the order parameter found for the lecithin chains. Possible explanations for the diminution of the order parameter for cholesteryl ester in bilayers are discussed.
D002788:Cholesterol Esters / Q000032:analysis; D003903:Deuterium; D004530:Egg Yolk; D005260:Female; D008081:Liposomes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D010168:Palmitates; D010713:Phosphatidylcholines / Q000032:analysis; D013499:Surface Properties
D002788:Cholesterol Esters; D008081:Liposomes; D010168:Palmitates; D010713:Phosphatidylcholines; D003903:Deuterium