ROLE OF LAMELLAR MEMBRANE-STRUCTURE IN TETHER FORMATION FROM BILAYER VESICLES
ROLE OF LAMELLAR MEMBRANE-STRUCTURE IN TETHER FORMATION FROM BILAYER VESICLES
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DOI：
10.1016/s0006-3495(92)81903-3
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发表时间：
1992-04-01
影响因子：
3.4
通讯作者：
WAUGH, RE
中科院分区：
文献类型：
--
作者：
BOZIC, B;SVETINA, S;WAUGH, RE
对微量移液管吸入的磷脂囊泡形成膜系链进行了理论分析。特别地，考虑到磷脂膜由接触但不连接的两层组成。双层的弹性能被认为是面积膨胀率、两个单层的相对膨胀率和弯曲的贡献之和。将囊泡吸入移液管中，并在远离移液管的方向的相对侧施加恒定的点力。囊泡的形状近似为带有半球形帽、球形部分和带有半球形帽的圆柱形系链的移液管中的圆柱形突出物。囊泡不同区域的尺寸是在囊泡体积固定的情况下，通过最小化囊泡的弹性能来获得的。系统参数值的范围被确定，在该范围内系绳可能存在。进行稳定性分析，显示哪些配置是稳定的。通过认识到局部弯曲能量本身并不能稳定囊泡的几何形状，并且在相对膨胀模量变得无限大的极限下，不能形成系链，从而确定了组成单层的相对膨胀和压缩的重要性。对实验可观测量之间的函数关系进行预测。在一份配套报告中，该分析的结果应用于系链形成的实验测量，并用于计算膜材料系数的值。
A theoretical analysis is presented of the formation of membrane tethers from micropipette-aspirated phospholipid vesicles. In particular, it is taken into account that the phospholipid membrane is composed of two layers which are in contact but unconnected. The elastic energy of the bilayer is taken to be the sum of contributions from area expansivity, relative expansivity of the two monolayers, and bending. The vesicle is aspirated into a pipette and a constant point force is applied at the opposite side in the direction away from the pipette. The shape of the vesicle is approximated as a cylindrical projection into the pipette with a hemispherical cap, a spherical section, and a cylindrical tether with a hemispherical cap. The dimensions of the different regions of the vesicle are obtained by minimizing its elastic energy subject to the condition that the volume of the vesicle is fixed. The range of values for the parameters of the system is determined at which the existence of a tether is possible. Stability analysis is performed showing which of these configurations are stable. The importance of the relative expansion and compression of the constituent monolayers is established by recognizing that local bending energy by itself does not stabilize the vesicle geometry, and that in the limit as the relative expansivity modulus becomes infinitely large, a tether cannot be formed. Predictions are made for the functional relationships among experimentally observable quantities. In a companion report, the results of this analysis are applied to experimental measurements of tether formation, and used to calculate values for the membrane material coefficients.