Cholesterol-multilipid interactions in bilayers

✍ Scribed by Leonard Finegold; Michael A. Singer

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 305 KB
• Volume: 58
• Category: Article
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(91)90122-r

✦ Synopsis

To extend our knowledge of model membrane systems based upon one lipid component, multi-lamellar bilayers were made of cholesterol with two phospholipids in equimolar ratio, and the enthalpy change AH of the main phase transition of the ternary mixture was measured by differential scanning calorimetry (DSC) as a function of increasing cholesterol concentration c. The lipids were saturated phosphatidylcholines CnPC of acyl chain length n, and as the n of the two lipids became more different (from C 13PC/CI4PC to CI4PC/CI5PC to CI4PC/C18PC to CI4PC/CI9PC) distinct breaks in the AH versus c plots were observed. These mixtures displayed only one broad DSC endotherm. Mixtures of an unsaturated lipid C18:1PC (dioleoyl) with CI6PC or with CI8PC showed two peaks, with each peak being associated with its parent lipid. However, the AH versus c plots for each of these peaks showed an initial independence of cholesterol concentration followed by a dependence on cholesterol concentration. These results indicate that, in lipid mixtures, the type of interaction of cholesterol with each lipid component depends on the concentration of cholesterol present.