Blok M C, van der Neut-Kok E C, van Deenen L L, de Gier J
Biochim Biophys Acta. 1975 Oct 6;406(2):187-96. doi: 10.1016/0005-2736(75)90003-6.
This paper describes experiments showing the importance of the fatty acid chain length on the barrier properties of liposomal bilayers, prepared from saturated lecithins, under conditions of lateral phase separation. 1. Above the gel to liquid crystalline phase transition temperature, liposomes prepared from saturated lecithins with 14 or more carbon atoms per acyl chain exist as stable bilayers, which are practically impermeable to ions. 2. At temperatures well above the transition temperature dilauroyl phosphatidylcholine liposomes exhibited osmotic shrinkage, which was dependent on the ionic size of the solute used to bring about the osmotic gradient, indicating that the permeation through these less stable bilayers takes place mainly via individual diffusion of the permeating ions. 3. An enhanced release of trapped potassium from liposomes was demonstrated in the vicinity of the transition temperature. The extent of the increase, however, depended strongly on the length of the paraffin chain. 4. From measurements of the shrinkage behaviour of liposomes in the vicinity of the transition temperature it is concluded that the increased permeability decreases with increasing diameter of the permeating ion. This finding implies that the increased permeability at the transition temperature cannot be ascribed to "macroscopic" rupture of the liposomal membrane. The maximum permeability in the vicinity of the Tc is discussed in terms of probability and size distribution of statistical pore formation at the boundaries of liquid and solid domains.
本文描述了一些实验，这些实验表明了脂肪酸链长度对在横向相分离条件下由饱和卵磷脂制备的脂质体双层膜屏障特性的重要性。1. 高于凝胶到液晶相转变温度时，由每个酰基链含有14个或更多碳原子的饱和卵磷脂制备的脂质体以稳定的双层膜形式存在，实际上对离子是不可渗透的。2. 在远高于转变温度的温度下，二月桂酰磷脂酰胆碱脂质体表现出渗透收缩，这取决于用于产生渗透梯度的溶质的离子大小，表明通过这些较不稳定双层膜的渗透主要通过渗透离子的个体扩散发生。3. 在转变温度附近，证明了脂质体中被困钾的释放增强。然而，增加的程度强烈取决于石蜡链的长度。4. 根据在转变温度附近脂质体收缩行为的测量结果得出结论，渗透率的增加随着渗透离子直径的增加而降低。这一发现意味着在转变温度下渗透率的增加不能归因于脂质体膜的“宏观”破裂。根据在液体和固体域边界处统计孔形成的概率和尺寸分布，讨论了Tc附近的最大渗透率。
