SHORT- AND LONG-RANGE FORCES BETWEEN MEMBRANE SURFACES

在溶剂中，表面之间的分离受以下几种因素支配 非特定的短程和长程力量，包括排斥力 水合作用和立体作用力以及吸引人的范德华作用力。 建议进行实验来测量和分析这些相互作用 在(1)几种类型的磷脂和磷脂- 胆固醇双分子层和(2)含有糖脂和 糖蛋白。 水合作用和立体作用力，它们提供了主要的障碍 到接近双分子层时，将作为一个函数来测量 用X射线衍射法分离相邻双分子层 已知渗透和水蒸气压缩的多层膜的分析 压力。电子密度分布将被用来确定 所应用的每个值的双层结构和流体间距 压力。X射线衍射量热法实验 旨在确定水合力对 溶剂分子的尺寸和结构，组成， 以及双层的性质。水合力将是 作为脂头组类型、头组的函数进行测量 双层平面上的关联(长程有序)， 膜成分的存在，如胆固醇、糖脂、 和正构烷基间苯二酚，以及界面电势。来自这些网站的数据 实验将被用来检验几个理论模型，以及 应提供可靠的关于 水合力。压力间隔的急剧向上断裂 在较小的两层间间隔时的关系将指示起始 立体障碍的影响。这些研究将表明 不同的磷脂、糖脂和糖蛋白修饰的 膜之间空间相互作用的大小和范围 表面。此外，还将使用压力-间隔关系 来确定范德华力的原点平面。这个 这个平面的精确位置和水合的大小 和立体作用力是计算 双分子层间的结合能及其定量分析 膜融合。

The separation between surfaces in solvent is governed by several non-specific short-and long-range forces, including the repulsive hydration and steric forces and the attractive van der Waals force. Experiments are proposed to measure and analyze these interactions between (1) several types of phospholipid and phospholipid- cholesterol bilayers and (2) bilayers containing glycolipids and glycoproteins. The hydration and steric forces, which provide the major barriers to the close approach of bilayers, will be measured as a function of separation between adjacent bilayers by x-ray diffraction analysis of multilayers compressed by known osmotic and vapor pressures. Electron density profiles will be used to determine the bilayer structure and fluid spacing for each value of applied pressure. X-ray diffraction and calorimetry experiments are designed to determine the dependence of the hydration force on the dimensions of the solvent molecule and the structure, composition, and properties of the bilayer. The hydration force will be measured as a function of lipid head group type, head group correlations (long-range order) in the plane of the bilayer, presence of membrane components such as cholesterol, glycolipids, and n-alkylresorcinol, and interfacial potential. Data from these experiments will be used to test several theoretical models, and should provide solid information on the physical basis of the hydration force. Sharp upward breaks in the pressure-spacing relation at small interbilayer separations will indicate the onset of steric hindrance. These studies will indicate the degree to which various phospholipids, glycolipids, and glycoproteins modify the magnitude and range of steric interactions between membrane surfaces. In addition, the pressure-spacing relations will be used to determine the plane of origin of the van der Waals force. The precise location of this plane and the magnitudes of the hydration and steric forces are essential parameters for calculations of interbilayer adhesion energies and for quantitative analyses of membrane fusion.