DIRECT MEASUREMENT OF FORCES BETWEEN MEMBRANES OF MACROMOLECULES

直接测量大分子膜之间的力

• 批准号: 3875586
• 负责人: V A PARSEGIAN
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3875586
• 关键词: cell membrane; chemical hydration; intermolecular interaction; macromolecule; membrane; membrane activity; membrane lipids; membrane model; membrane structure; nuclear magnetic resonance spectroscopy; phospholipids; protein structure function

The ability to measure directly the forces between membranes or between macromolecules is creating a new logic for thinking about molecular assembly and folding. The outstanding feature of interaction is that as molecules or membranes approach contact, the important work of approach involves removal of organized water solvent from the apposing surfaces. These "hydration forces" are now recognized to act in materials as diverse as lipid bilayers, DNA double helices, and stiff linear polysaccharides. Until now, only force or energy vs. surface separation between molecules or membranes has been measured. During the current year, the "entropy" and "enthalpy" of release water, as a function of the distance between macromolecules, has been successfully extracted. The first phase of a systematic study of forces between polysaccharides has also been completed. Again, for these materials as for nucleic acids and lipids, one sees exponentially decaying "hydration" forces between molecules approaching contact. A theory of lipid bilayer forces that claims to relate the "dipole ]potential" set up by the lipid polar groups to the perturbation of water near the lipid interface is being tested. A combined osmotic stress, x-ray diffraction, NMR and ion transport study shows that the correlation demanded by the theory does not exist. Bilayers of synthetic lipids, thought from the work of others not to show strong hydration forces, have now shown a very strong version of this force when observed by our direct, osmotic stress method. Finally, a surprisingly easy transition between lamellar and non-lamellar packing of lipids whose occurrence may be related to easy rearrangement of cell membrane lipids in secretion and fusion is being investigated.

能够直接测量膜之间或膜与膜之间的力， 大分子正在创造一种新的逻辑来思考分子 组装和折叠。互动的突出特点是， 分子或膜接近接触，接近的重要工作 包括从相对表面除去有机水溶剂。 这些“水化力”现在被认为在材料中起作用， 如脂质双层、DNA双螺旋和刚性线性多糖。 到目前为止，只有力或能量与分子之间的表面分离或 膜已被测量。在本年度，“熵”和 释放水的“焓”，作为 大分子，已成功提取。 系统研究多糖之间作用力的第一阶段， 也已经完成。同样，对于这些材料，如对于核酸和 在脂质之间，人们看到呈指数衰减的“水合”力， 分子接近接触。 一种脂双层力的理论，声称与“偶极子” 脂质极性基团对水的扰动所建立的”[]电位 正在测试脂质界面附近。结合渗透压x射线 衍射、核磁共振和离子输运研究表明， 理论所要求的不存在。 双层的合成脂质，从别人的工作认为不显示 强大的水化力，现在已经显示出这种力量的非常强大的版本 当通过我们的直接渗透压方法观察时。 最后，令人惊讶的是， 脂质的堆积，其发生可能与 正在研究细胞膜脂质的分泌和融合。