31p-NMR investigations of phase separation in phosphatidylcholine/phosphatidylethanolamine mixtures.
A phase diagram of DPPC-DPPE mixture is constructed by an analysis of the temperature dependence of the anisotropy of chemical shift of the 31P-NMR signals of the individual components. At each temperature the phase state of the individual phospholipids is described. Thus 31P-NMR is more informative than other methods such as ESR, DSC and fluorescence. The measurements confirm the conclusion of other authors that there is a phase separation in the gel state. In the temperature range of the phase transition the molecules are exchanged rapidly between liquid-crystalline and solid regions. In addition to the phase diagram a theoretical approach is applied to estimate the relative distribution of like and unlike molecules in the liquid-crystalline state and a nonrandom distribution is found.
D009682:Magnetic Resonance Spectroscopy; D008433:Mathematics; D008567:Membranes, Artificial; D010713:Phosphatidylcholines / Q000032:analysis*; D010714:Phosphatidylethanolamines / Q000032:analysis*; D013696:Temperature
D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines