Evidence of entropic contribution to ''hydration'' forces between membranes .2. Temperature dependence of the ''hydration'' force: A small angle neutron scattering study
Evidence of entropic contribution to ''hydration'' forces between membranes .2. Temperature dependence of the ''hydration'' force: A small angle neutron scattering study
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DOI：
10.1016/s0022-2860(96)09276-9
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发表时间：
1996-09-30
影响因子：
3.8
通讯作者：
Teixeira, J
中科院分区：
文献类型：
--
作者：
Gordeliy, VI;Cherezov, VG;Teixeira, J
利用中子小角散射技术研究了1，2-二肉豆蔻酰-sn-甘油-磷脂酰胆碱（DMPC）和1，2-二棕榈酰-sn-甘油-磷脂酰胆碱（DPPC）膜在D2 O（1%w/w）中的结构参数随温度的变化，并采用一种新的方法确定了膜间距d（w）.从溶液中多层膜的衍射峰的位置确定重复距离d。膜的厚度d（L）由单个囊泡的小角散射计算。膜间距离d，是由d和d（L）之差确定的。在T > 65 ℃时，重复距离和膜间距离随温度的升高而显著增加。但随着温度的升高，脂双层厚度不断减小。衍射峰的积分强度显著降低，表明膜间距的温度依赖性可以用膜表面的类湍流热涨落和膜起伏的增加引起的熵力的增加来解释。膜的弯曲刚度降低，使膜的起伏度增大。弯曲刚度随温度的显著变化不能仅用双层厚度的减小来解释。随着温度的升高，凸起幅度的增加导致弯曲刚度的急剧下降。
The temperature dependence of structural parameters of 1,2-dimiristoyl-sn-glycero-phosphatidylcholine (DMPC) and 1,2-dipalmitoyl-sn-glycero-phosphatidylcholine (DPPC) membranes in D2O (1% w/w of lipid) has been studied via neutron small-angle scattering.A new approach was used to determine the intermembrane distance d(w). The repeat distance d was determined from the position of diffraction peaks from multilamellar membranes in solution. The thickness of membranes d(L) was calculated from small-angle scattering with single vesicles. The intermembrane distance d, was determined as the difference between d and d(L).Repeat and intermembrane distances increase considerably with temperature increase at T > 65 degrees C. However, the lipid bilayer thickness decreases continuously with the increase of temperature. The integral intensities of the diffraction peaks decrease considerably.It is shown here that the temperature dependence of the intermembrane distance can be explained by the increase of entropic forces due to an increase of protrusion-like thermal fluctuations of the membrane surface and membrane undulations. The membrane undulations increase due to the decrease of membrane bending rigidity. Considerable changes in the bending rigidity with temperature cannot be explained only by the reduction of the bilayer thickness. The increase of protrusion amplitude with temperature increase results in a dramatic decrease of the bending rigidity.