DIRECT INTERACTION FORCE MEASUREMENTS BETWEEN BILAYERS

表面活性剂磷脂膜的稳定性和转化 微结构和其他大分子由天平控制 当这些胶体材料 相隔的距离很小(5到100埃)。一项基本原则 了解许多重要的生物过程，包括膜 细胞黏附与融合、囊泡形成与抗体受体 识别需要对这些短程的性质有所了解 胶体力，它们如何依赖于距离以及它们如何被修改 通过表面形态的变化。表面作用力装置允许 这些胶体力可以用距离分辨率直接测量 从接触到大间隔的+或-1埃(10,000埃)。 用于测力的分子光滑云母将被涂覆 用聚合表面活性剂的单分子层来生成平坦的分子 光滑的碳氢化合物-水界面。 第一系列实验将涉及力与距离的关系。 当两个碳氢化合物表面一起移动时的测量结果 水和其他极性溶剂。这将确立 导致表面活性剂聚集的疏水性作用力 和脂类形成微结构(胶束、双层、膜， 囊泡、微管等)。在第二系列测量中， 磷脂单分子层将被吸附到碳氢化合物底物上，并 将确定各种脂头基团的相互作用力。 两个磷脂单分子层的接近相当于将 两个平面双层膜结合在一起。我们的目标是获取证据 从非常强的排斥力转变为稳定的水合力 到同样强大的有吸引力的水合力，从而导致 膜融合。在第三系列实验中，髓鞘碱性蛋白 而血因子V将被吸收到卵磷脂单层上，并 脂-蛋白(-蛋白)-脂双层的粘附性 直接测量的交互作用。这样的相互作用在 稳定保护神经的多层膜结构 轴突。由表面力装置提供的信息是唯一的， 美国唯一的这类机构设在加州大学 明尼苏达州。

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.