Separation of liquid phases in giant vesicles of ternary mixtures of phospholipids and cholesterol
Separation of liquid phases in giant vesicles of ternary mixtures of phospholipids and cholesterol
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DOI：
10.1016/s0006-3495(03)74726-2
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发表时间：
2003-11-01
影响因子：
3.4
通讯作者：
Keller, SL
中科院分区：
文献类型：
--
作者：
Veatch, SL;Keller, SL
我们使用荧光显微镜直接观察巨大单层囊泡中的液体相。我们发现，一长串高熔点(饱和)脂、低熔点(通常不饱和)脂和胆固醇的三元混合物会产生液态区。对于DPPC/DOPC/CHOL这一模型混合物，我们绘制了整个三元体系的相界图。对于这种混合物，我们在广泛的脂肪组成和温度范围内观察到两个共存的液体相，一个相富含不饱和脂肪，另一个富含饱和脂肪和胆固醇。我们发现链熔化温度和混溶转变温度之间的简单关系对磷脂酰胆碱和神经鞘磷脂都适用。我们通过改变温度和用β-环糊精耗尽胆固醇来实验跨越相容界限。囊泡中的液体区域表现出有趣的行为：它们相互碰撞和结合，可以指成条纹，并可以从囊泡中凸出。到目前为止，我们还没有观察到仅在二元脂质混合物中的宏观相分离。
We use fluorescence microscopy to directly observe liquid phases in giant unilamellar vesicles. We find that a long list of ternary mixtures of high melting temperature ( saturated) lipids, low melting temperature ( usually unsaturated) lipids, and cholesterol produce liquid domains. For one model mixture in particular, DPPC/DOPC/Chol, we have mapped phase boundaries for the full ternary system. For this mixture we observe two coexisting liquid phases over a wide range of lipid composition and temperature, with one phase rich in the unsaturated lipid and the other rich in the saturated lipid and cholesterol. We find a simple relationship between chain melting temperature and miscibility transition temperature that holds for both phosphatidylcholine and sphingomyelin lipids. We experimentally cross miscibility boundaries both by changing temperature and by the depletion of cholesterol with beta-cyclodextrin. Liquid domains in vesicles exhibit interesting behavior: they collide and coalesce, can finger into stripes, and can bulge out of the vesicle. To date, we have not observed macroscopic separation of liquid phases in only binary lipid mixtures.