Ceramide Drives Cholesterol Out of the Ordered Lipid Bilayer Phase into the Crystal Phase in 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/Cholesterol/Ceramide Ternary Mixtures

• DOI: 10.1021/bi060610x
• Publication Date: 2006-09-23T11:09:28Z
• Authors: Md Rejwan Ali; Kwan Hon Cheng; Juyang Huang
• Keywords: POPC

The effect of brain ceramide on the maximum solubility cholesterol in ternary mixtures 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), cholesterol, and was investigated at 37 °C by a oxidase (COD) reaction rate assay optical microscopy. COD showed sharp increase chemical potential as mole fraction approaches limit. A decline found after formation crystals. POPC bilayers determined to be 68 ± 2 mol % We that has much higher affinity for ordered than decreases with content. More significantly, displacement follows 1:1 relation. At limit, adding one more molecule lipid bilayer drives out into crystal phase, is incapable displacing from phase. On basis these findings, phase diagram POPC/cholesterol/ceramide mixture constructed. behaviors can explained umbrella model. Both have small polar headgroups relatively large nonpolar bodies. In PC bilayer, compete coverage neighboring prevent exposure their bodies water. This competition results well raft domains.