Hagen J P, McConnell H M
Stauffer Laboratory of Physical Chemistry, Department of Chemistry, Stanford University CA 94305-5080, USA.
Biochim Biophys Acta. 1996 Apr 26;1280(2):169-72. doi: 10.1016/0005-2736(96)00009-0.
Epifluorescence microscopy has been used previously to study coexisting liquid phases in lipid monolayers of dihydrocholesterol and dimyristoylphosphatidylcholine at the air/water interface. This binary mixture has a critical point at room temperature (22 degrees C), a monolayer pressure of approx. 10 mN/m, and a composition in the vicinity of 20-30 mol% dihydrocholesterol. It is reported here that this critical pressure can be lowered, raised, or maintained constant by systematically replacing molecules of this phosphatidylcholine with molecules of a phosphatidylethanolamine, or an unsaturated phosphatidylcholine, or mixtures of the two, while maintaining the dihydrocholesterol concentration at 20 mol%. Thus, even complex mixtures of lipids may be characterized by a single, well-defined second-order phase transition. In principle, such transitions might be found in biological membranes.
落射荧光显微镜先前已被用于研究二氢胆固醇和二肉豆蔻酰磷脂酰胆碱在空气/水界面的脂质单分子层中共存的液相。这种二元混合物在室温（22摄氏度）、单层压力约为10 mN/m以及二氢胆固醇含量在20 - 30 mol%附近时存在一个临界点。本文报道，通过用磷脂酰乙醇胺分子、不饱和磷脂酰胆碱分子或两者的混合物系统地取代这种磷脂酰胆碱分子，同时将二氢胆固醇浓度保持在20 mol%，这个临界压力可以降低、升高或保持恒定。因此，即使是复杂的脂质混合物也可能具有单一的、明确界定的二级相变特征。原则上，这种相变可能在生物膜中被发现。
