Structure and thermotropic behaviour of mixed choline phospholipid model membranes
Structure and thermotropic behaviour of mixed choline phospholipid model membranes
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DOI：
10.1107/s0021889897001386
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发表时间：
1997-10-01
影响因子：
6.1
通讯作者：
Lohner, K
中科院分区：
文献类型：
--
作者：
Degovics, G;Latal, A;Lohner, K
磷脂酰胆碱和鞘磷脂是哺乳动物细胞膜中最丰富的脂质，是血小板或红细胞以及脂蛋白的脂质单层的主要组分。一般的努力已经致力于阐明无处不在的膜组分胆固醇与这些胆碱磷脂的相互作用，但很少有研究报道磷脂本身之间的相互作用。纯鞘磷脂脂质体在生理温度下发生凝胶相向液晶相转变，而棕榈油酰磷脂酰胆碱在273-323 K温度范围内发生液晶相转变。这两种磷脂在液晶相中以所有摩尔比混溶，其特征在于所有二元脂质混合物具有非常相似的层状重复距离。与混合脂质囊泡相比，纯鞘脂脂质体的凝胶相表现出明显更小的层状重复距离，对于纯鞘磷脂，其随温度略微增加（66.9-69.2埃）。同时，观察到改变的烃链堆积。在10mol%磷脂酰胆碱存在下获得类似的衍射图。然而，在磷脂酰胆碱-鞘磷脂混合物中20 - 60摩尔%磷脂酰胆碱的组成范围内，凝胶相中的层状重复距离显著增加，并且在相变以下几乎保持恒定（约75埃）。
Phosphatidylcholines and sphingomyelins are among the most abundant lipids in mammalian cell membranes, being major components of platelets or erythrocytes, and of the lipid monolayer of lipoproteins. General efforts have been devoted to the elucidation of the interaction of the ubiquitous membrane component cholesterol with these choline phospholipids, but fewer studies have been reported on the interaction between the phospholipids themselves. A gel to liquid-crystalline phase transition was observed for pure sphingomyelin liposomes at physiological temperature, while palmitoyloleoyl phosphatidylcholine adopts a liquid-crystalline phase in the temperature range 273-323 K. The two phospholipids are miscible at all molar ratios in the liquid-crystalline phase, characterized by very similar lamellar repeat distances for all binary lipid mixtures. The gel phase of pure sphingolipid liposomes exhibited a markedly smaller lamellar repeat distance as compared to mixed lipid vesicles, which increased slightly with temperature for the pure sphingomyelin (66.9-69.2 Angstrom). Concomitantly, altered hydrocarbon chain packing was observed. Similar diffractograms were obtained in the presence of 10 mol% phosphatidylcholine. However, in the composition range between 20 and 60 mol% phosphatidylcholine in the phosphatidylcholine-sphingomyelin admixture, the lamellar repeat distance in the gel phase was markedly increased and remained almost constant (around 75 Angstrom) below the phase transition.