POLYMORPHIC PHASE BEHAVIOR OF LIPID MIXTURES AS DETECTED BY P-31 NMR - EVIDENCE THAT CHOLESTEROL MAY DESTABILIZE BILAYER STRUCTURE IN MEMBRANE SYSTEMS CONTAINING PHOSPHATIDYLETHANOLAMINE
POLYMORPHIC PHASE BEHAVIOR OF LIPID MIXTURES AS DETECTED BY P-31 NMR - EVIDENCE THAT CHOLESTEROL MAY DESTABILIZE BILAYER STRUCTURE IN MEMBRANE SYSTEMS CONTAINING PHOSPHATIDYLETHANOLAMINE
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DOI：
10.1016/0005-2736(78)90417-0
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发表时间：
1978-01-01
期刊：
影响因子：
--
通讯作者：
DEKRUIJFF, B
中科院分区：
文献类型：
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作者：
CULLIS, PR;DEKRUIJFF, B
31P核磁共振是研究水合磷脂在过量水中多晶相行为的一种有用的分析技术。这种可能性的产生是由于磷脂的横向扩散，在非双层相中，产生额外的运动平均机制。这导致脂质在双层相、六方（H11）相或反胶束、立方或菱形相中具有独特的31P NMR谱。研究了大豆磷脂酰乙醇胺以及大豆磷脂酰乙醇胺与饱和和不饱和磷脂酰胆碱的混合物的多晶相行为。当温度降到10度以下时。C，大豆磷脂酰乙醇胺倾向于进入双层相。在较高的温度下（0-50度）。C)六方（H11）相。加入50 mol%蛋黄或（液晶）16:0/16:0磷脂酰胆碱足以稳定双层相。在18:1c/18:1c磷脂酰乙醇胺中加入等摩尔胆固醇导致双层-六方（H11）转变向较低温度移动。在大豆磷脂酰乙醇胺/35 mol%蛋黄磷脂酰胆碱混合物中加入等摩尔胆固醇使双层相的组分不稳定。在含有30 mol% 16:0/16:0磷脂酰胆碱的混合物中加入胆固醇可以稳定双层结构。这些结果是根据含有高浓度磷脂酰乙醇胺的生物膜含有很少或没有胆固醇的观察结果进行讨论的。胆固醇可能被排除在外，因为它的存在会破坏双分子层结构。生物膜中脂类的双层结构可能与其他可用相处于动态平衡状态。鉴于这种可能性，提出了生物膜中触发器现象的一种机制。
31P NMR is a useful analytical technique for the study of the polymorphic phase behavior of hydrated phospholipids in excess water. Such possibilities arise due to lateral diffusion of phospholipids which, in non-bilayer phases, produce additional motional averaging mechanisms. This results in distinctive 31P NMR spectra for lipids in the bilayer phase, hexagonal (H11) phase or phases such as the inverted micellar, cubic or rhombic. The polymorphic phase behavior of soya phosphatidylethanolamine and mixtures of soya phosphatidylethanolamine with saturated and unsaturated phosphatidylcholines was investigated. As the temperature is decreased below 10.degree. C, soya phosphatidylethanolamine tends to enter the bilayer phase. At higher temperatures (0-50.degree. C) the hexagonal (H11) phase is observed. The addition of 50 mol% egg yolk or (liquid-crystalline) 16:0/16:0 phosphatidylcholine is sufficient to stabilize the bilayer phase. The addition of equimolar cholesterol to 18:1c/18:1c phosphatidylethanolamine results in the bilayer-hexagonal (H11) transition moving to lower temperatures. The addition of equimolar cholesterol to soya phosphatidylethanolamine/35 mol% egg yolk phosphatidylcholine mixtures destabilizes the component in the bilayer phase. The addition of cholesterol to mixtures containing 30 mol% 16:0/16:0 phosphatidylcholine stabilizes the bilayer configuration. These results are discussed with regard to the observation that biological membranes containing high concentrations of phosphatidylethanolamine contain little or no cholesterol. Cholesterol may be excluded because its presence would disrupt bilayer structure. The bilayer structure of lipids in biomembranes may be in dynamic equilibrium with other available phases. In the light of such possibilities a mechanism of flip-flop phenomena in biological membranes is suggested.