DIRECT MEASUREMENTS OF FORCES BETWEEN PHOSPHATIDYLCHOLINE AND PHOSPHATIDYLETHANOLAMINE BILAYERS IN AQUEOUS-ELECTROLYTE SOLUTIONS
DIRECT MEASUREMENTS OF FORCES BETWEEN PHOSPHATIDYLCHOLINE AND PHOSPHATIDYLETHANOLAMINE BILAYERS IN AQUEOUS-ELECTROLYTE SOLUTIONS
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DOI：
10.1021/bi00338a020
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发表时间：
1985-01-01
期刊：
影响因子：
2.9
通讯作者：
ISRAELACHVILI, J
中科院分区：
文献类型：
--
作者：
MARRA, J;ISRAELACHVILI, J
我们报告了水溶液中各种磷脂酰胆碱和磷脂酰乙醇胺双层之间完整双层间力定律（力与距离）的直接测量。首先将双层沉积在分子光滑（云母）表面上，然后以 1 A 的分辨率测量双层间力。确定了三种类型的力：吸引的范德华力、排斥的静电（双层）力和（在短程）排斥的空间水合力。由离子结合产生的双层力在一价盐溶液（例如高达 1 M 的 NaCl）中微不足道，但在含有毫摩尔水平的 CaCl2 和 MgCl2 的溶液中已经存在，产生的力与理论非常一致。 Ca2+ 比 Mg2+ 结合更强，并且两者在流体状态下与卵磷脂双层的结合较少 (T > Tc)。电荷平面与负磷酸基团的位置重合，而范迪尔华力的有效原点平面为 4-5 ANG。更远的地方。在水中，卵磷脂和.apprx 的粘附能在 0.10-0.15 erg/cm2 范围内。磷脂酰乙醇胺为 0.8 erg/cm2。粘附能随着盐的添加而变化，这是由于双层排斥力和杂化力的变化而不是由于吸引的范德华力的变化。短程排斥力在 10-30 ANG 的间隔处平衡范德华力。是由于水合和空间排斥的组合，后者是由头部组的热运动和流体双层的厚度波动（高于 Tc）引起的。还得出结论，双层融合不仅仅与双层间力定律相关。
We report direct measurements of the full interbilayer force laws (force vs. distance) between bilayers of various phosphatidylcholines and phosphatidylethanolamine in aqueous solutions. Bilayers were first deposited on molecularly smooth (mica) surfaces and the interbilayer forces then measured at a resolution of 1 A. Three types of forces were identified: attractive van der Waals forces, repulsive electrostatic (double-layer) forces, and (at short range) repulsive steric hydration forces. Double-layer forces, which arise from ion binding, were insignificant in monovalent salt solutions, e.g., NaCl up to 1 M, but were already present in solutions containing millimolar levels of CaCl2 and MgCl2, giving rise to forces in excellent agreement with theory. Ca2+ binds more strongly than Mg2+, and both bind less to lecithin bilayers in the fluid state (T > Tc). The plane of charge coincides with the location of the negative phosphate groups, while the effective plane of origin of the van deer Waals force is 4-5 .ANG. farther out. In water, the adhesion energies are in the range 0.10-0.15 erg/cm2 for lecithins and .apprx. 0.8 erg/cm2 for phosphatidylethanolamine. The adhesion energies vary on addition of salt due to changes in the repulsive double-layer and hybridation forces rather than to a change in the attractive van der Waals force. The short-range repulsive forces which balance the van der Waals force at separations of 10-30 .ANG. are due to a combination of hydration and steric repulsions, the latter arising from thermal motions of head groups and thickness fluctuations of fluid bilayers (above Tc). It is also concluded that bilayer fusion is not simply related to the interbilayer force law.