Bending elasticities of model membranes: Influences of temperature and sterol content
Bending elasticities of model membranes: Influences of temperature and sterol content
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DOI：
10.1016/s0006-3495(97)78905-7
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发表时间：
1997-06-01
影响因子：
3.4
通讯作者：
Bothorel, P
中科院分区：
文献类型：
--
作者：
Meleard, P;Gerbeaud, C;Bothorel, P
通过电成型获得并通过相差视频显微镜观察的巨型脂质体显示出源自布朗运动的自发变形，在准球形囊泡的情况下，其特征仅在于两个参数，即膜张力西格玛和弯曲弹性k(c)。对于含有二肉豆蔻酰磷脂酰胆碱 (DMPC) 或 10 mol% 胆固醇/DMPC 混合物的脂质体，膜的机械性能 k(c) 显示为温度依赖于接近主（热致）相变温度 T-m。在 DMPC/胆固醇双层的情况下，我们还获得了弯曲弹性与相应的温度/胆固醇分子比相图之间关系的证据。在 30 摄氏度下，含有 30% 甾醇比例的 DMPC/胆固醇与 DMPC/胆固醇硫酸盐双层的比较表明，k(c) 与双层的表面电荷密度无关。最后，如果我们参考 DMPC/胆固醇双层，红细胞 (RBC) 总脂质提取物的弯曲弹性导致 37 摄氏度下的 k(c) 非常低。理论上，在 25 摄氏度下，无胆固醇红细胞脂质提取物的低弯曲弹性似乎与相共存有关，这可以通过固体不新鲜的 P-31-NMR 观察到。在相同温度下，与在 DMPC 膜中观察到的高胆固醇比率相比，含胆固醇的红细胞脂质提取物膜显示出弯曲常数的增加。
Giant liposomes obtained by electroformation and observed by phase-contrast video microscopy show spontaneous deformations originating from Brownian motion that are characterized, in the case of quasispherical vesicles, by two parameters only, the membrane tension sigma and the bending elasticity k(c). For liposomes containing dimyristoyl phosphatidylcholine (DMPC) or a 10 mol% cholesterol/DMPC mixture, the mechanical property of the membrane, k(c), is shown to be temperature dependent on approaching the main (thermotropic) phase transition temperature T-m. In the case of DMPC/cholesterol bilayers, we also obtained evidence for a relation between the bending elasticity and the corresponding temperature/cholesterol molecular ratio phase diagram. Comparison of DMPC/cholesterol with DMPC/cholesterol sulfate bilayers at 30 degrees C containing 30% sterol ratio shows that k(c) is independent of the surface charge density of the bilayer, Finally, bending elasticities of red blood cell (RBC) total lipid extracts lead to a very low k(c) at 37 degrees C if we refer to DMPC/cholesterol bilayers. At 25 degrees C theory low bending elasticity of a cholesterol-free RBC lipid extract seems to be related to a phase coexistence, as it can be observed by solid-stale P-31-NMR. At the same temperature, the cholesterol-containing RBC lipid extract membrane shows an increase in the bending constant comparable to the one observed for a high cholesterol ratio in DMPC membranes.