Cholesterol in condensed and fluid phosphatidylcholine monolayers studied by epifluorescence microscopy.

摘要: Epifluorescence microscopy was used to investigate the effect of cholesterol on monolayers dipalmitoylphosphatidylcholine (DPPC) and 1 -palmitoyl-2-oleoyl phosphatidylcholine (POPC) at 21 +/- 2 degrees C using mol% 1-palmitoyl-2-[12-[(7-nitro-2–1, 3-benzoxadizole-4-yl)amino]dodecanoyl]phosphatidylcholine (NBD-PC) as a fluorophore. Up 30 in DPPC decreased amounts probe-excluded liquid-condensed (LC) phase all surface pressures (pi), but did not POPC, which remained liquid-expanded (LE) pi. At low pi (2–5 mN/m), 10 or more induced lateral separation into dark light probe-rich regions. In POPC monolayers, observed when > or=40 present. The with increased concentrations these lipid may be result segregation cholesterol-rich domains ordered fluid phases that preferentially exclude fluorescent probe. With increasing pi, could transformed from heterogeneous appearance homogeneous phase, manner dependent content. packing density acyl chains determinant interaction (PC), because transformations monolayer texture were phospholipid (PL)/sterol mixtures having similar molecular areas. high (41 elongated crystal-like structures containing 80–100 cholesterol, grew size compressed after collapse. This observation associated crystallization