Magnetically induced orientation of phosphatidylcholine membranes.
Magnetically induced orientation of phosphatidylcholine membranes.
复制标题
磷脂酰胆碱膜的磁诱导取向。
DOI：
10.1016/0005-2736(93)90316-r
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Pidgeon,C
中科院分区：
文献类型：
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作者：
Qiu,X;Mirau,PA;Pidgeon,C
由天然磷脂制备的脂质双层在磁场中取向，其中脂质分子的长轴垂直于磁场。在高（11.7特斯拉（T））、中（9.36 T）和低（4.68 T）磁场强度下使用由天然和合成磷脂酰胆碱类似物制备的脂质聚集体研究了这种磁诱导取向。磷脂酰胆碱类似物含有饱和的双酰化链（12至16个碳/链）表现出广泛的取向的脂质时，发生双层形成温和的水合条件。温和水合涉及在高于主要相变（Tm）105 -10°C的温度下在过量水中孵育干燥的磷脂酰胆碱脂质膜;偶尔需要用手短暂摇动或涡旋以完全分散脂质。双层形成的方法显着影响的量的脂质定向在磁场中。因此，在11.7 T磁场下，高于Tmin的二肉豆蔻酰磷脂酰胆碱（DMPC）双层的超分子结构（和%取向）为SUV（0%）、LUV（15%）、SPLV（140%）、涡旋MLV（160%）和非涡旋MLV（190%）。通过REV方法制备的单层囊泡在11.7 T下表现出与通过冻融循环制备的LUV相似的取向。通过温和水化制备的eggPC水分散体在11.7 T下表现出约40%的取向，如果向膜中加入30%的胆固醇，则其降低至约30%的取向。因此，磁取向的双层似乎是一个普遍现象，饱和和不饱和的天然磷脂，无论是有或没有胆固醇在膜中。
Lipid bilayers prepared from natural phospholipids orient in magnetic fields with the long axis of the lipid molecules perpendicular to the magnetic field. This magnetically induced orientation was studied at high (11.7 Tesla (T)), mid (9.36 T), and low (4.68 T) magnetic field strengths using lipid aggregates prepared from natural and synthetic phosphatidylcholine analogs. Phosphatidycholine analogs containing saturated diacylated chains (12 to 16 carbons/chain) exhibited extensive orientation of the lipid when bilayer formation occurred by gentle hydration conditions. Gentle hydration involved incubating dried phosphatidylcholine lipid films in excess water at temperatures that were ∼ 5–10°C above the main phase transition (Tm); brief shaking or swirling by hand was occasionally needed to completely disperse the lipids. The method of bilayer formation significantly influenced the amount of lipid that orients in magnetic fields. Thus the supramolecular structures (and % orientation) aboveTmin an 11.7 T field of dimyristoylphosphatidylcholine (DMPC) bilayers are SUV (0%), LUV (∼ 15%), SPLV (∼ 40%), vortexed-MLV (∼ 60%) and non-vortexed MLV (∼ 90%). Single layered vesicles prepared by the REV method exhibited orientation at 11.7 T similar to LUV prepared by freeze thaw cycles. Aqueous dispersions of eggPC prepared by gentle hydration exhibit ∼40% orientation at 11.7 T which decreased to ∼30% orientation if 30% cholesterol is added to the membrane. Magnetic orientation of bilayers thus appears to be a general phenomenon for both saturated and unsaturated natural phospholipids either with or without cholesterol in the membrane.