DIRECT INTERACTION FORCE MEASUREMENTS BETWEEN BILAYERS

磷脂膜、表面活性剂的稳定性和转化 微观结构和其他大分子由平衡控制 吸引力和排斥力之间的关系， 以非常小的距离（5到100埃）分开。 一项基本 了解许多重要的生物过程，包括膜 细胞粘附和融合、囊泡形成和抗体-受体 识别需要了解这些短距离的性质， 胶体力，它们如何依赖于距离，以及它们如何被修改 表面形态的变化。 表面力装置允许 这些胶体力可以用距离分辨率直接测量 从接触到大的分离（10，000埃）为+或-1埃。 用于力测量的分子光滑云母将被涂覆 与聚合表面活性剂单层接触， 光滑的烃-水界面。 第一系列的实验将涉及力与距离 测量的两个碳氢化合物表面，因为他们一起移动， 水和其它极性溶剂。 这将确定 导致表面活性剂聚集的疏水力 和脂质以形成微结构（胶束，双层，膜， 囊泡、微管等）。 在第二系列测量中， 磷脂单层将被吸附到烃基质上 将确定各种脂质头基的相互作用力。 两个磷脂单层的方法相当于将 两个平面双层膜。 我们的目标是获得证据， 一种从非常强的排斥水合力的变化， 膜具有同样强的吸引力， 膜融合 在第三系列实验中，髓鞘碱性蛋白 和血液因子V将被吸收到卵磷脂单层上， 脂质-蛋白质（-蛋白质）-脂质形成的双层粘附 直接测量的交互。 这种相互作用在以下方面很重要： 稳定保护神经的多层膜结构 轴突 由表面力设备提供的信息是唯一的， 美国唯一的这样的设备位于密歇根大学， 明尼苏达

The stability and transformation of phospholipid membranes, surfactant microstructures and other macromolecules are controlled by the balance between attractive and repulsive forces when these colloidal materials are separated by very small distances (5 to 100 angstroms). A fundamental understanding of many important biological processes including membrane cell adhesion and fusion, vesicle formation and antibody-receptor recognition requires a knowledge of the nature of these short-range colloidal forces, how they depend on distances and how they can be modified by changes in surface morphology. The surface force apparatus permits these colloidal forces to be directly measured with a distance resolution of + or - 1 angstrom from contact to large separation (10,000 angstroms). The molecularly smooth mica used in the force measurements will be coated with a monolayer of polymerized surfactant to generate a flat molecularly smooth hydrocarbon-water interface. The first series of experiments will involve force vs. distance measurements for the two hydrocarbon surfaces as they are moved together in water and other polar solvents. This will establish the nature of hydrophobic forces which are responsible for the aggregation of surfactants and lipids to form microstructures (micelles, bilayers, membranes, vesicles, microtubules, etc.). In a second series of measurements, phospholipid monolayers will be adsorbed onto the hydrocarbon substrate and the interaction forces for various lipid head groups will be determined. The approach of the two phospholipid monolayers is equivalent to bringing together two planar bilayer membranes. The goal is to obtain evidence for a change from very strong repulsive hydration forces which stabilize membranes to equally strong attractive hydration forces which lead to membrane fusion. In a third series of experiments, myelin basic protein and blood factor V will be absorbed onto the lecithin monolayer and the adhesion of bilayers resulting from lipid-protein(-protein)-lipid interaction directly measured. Such interactions are important in stabilizing the multilayered membrane structure that protects the nerve axon. The information provided by the surface force apparatus is unique, the only such apparatus in the U.S. is located at the University of Minnesota.