Phase separations in binary and ternary cholesterol-phospholipid mixtures.
A pair of recent studies has reopened debate on the subject of phase separations in model bilayer mixtures of cholesterol (Chol) and dipalmitoyl-phosphatidylcholine (DPPC). Fluorescence microscopy methods have not been able to detect phase separations in binary DPPC-Chol mixtures that have been inferred from NMR studies. However, micron-scale phase-separated liquid domains are observed by fluorescence in ternary mixtures of DPPC, Chol, and diphytanoyl-phosphatidylcholine (DiPhyPC). Here, a model of condensed complexes of Chol and DPPC is used to account for these results. In particular, it is shown that the orientation of tie-lines in ternary mixtures of DiPhyPC/DPPC/Chol is compatible with phase separation in binary DPPC/Chol mixtures.
Radhakrishnan
Arun
A
Department of Biochemistry, Weill Cornell Medical College, New York, New York, USA. arun314@yahoo.com
D002784:Cholesterol / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D010655:Phenylenediamines / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics
D008051:Lipid Bilayers; D010655:Phenylenediamines; D002784:Cholesterol; C004845:N,N'-diphenyl-4-phenylenediamine