DIRECT MEASUREMENT OF FORCES BETWEEN MEMBRANES OR MACROMOLECULES

直接测量膜或大分子之间的力

• 批准号: 2571580
• 负责人: V A PARSEGIAN
• 金额: --
• 依托单位: CENTER FOR INFORMATION TECHNOLOGY
• 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/2571580
• 关键词: DNA; cell osmotic pressure; chemical hydration; hydropathy; intermolecular interaction; lipid bilayer membrane; macromolecule; measurement; membrane activity; polysaccharides; surface property

The theme of this work is to develop a useful, accurate science of forces that organize biomolecules. To this end we have concentrated our efforts t measure forces between proteins, DNA double helices, and polysaccharides. The Osmotic Stress method for direct force measurements is winning widespread use around the world. Our LSB home page contains a ~living handbook~ of osmotic stress data and calibration curves. Records indicate that our home page is sometimes accessed as often as once every couple of minutes. The latest work on DNA forces combines osmotic stress with SAXS and polarization microscopy. Use of synchrotron radiation as well as ordinary x ray sources has shown several different forms of molecular packing, including a cholesteric phase characterized by great motional freedom (dialysis experiments at low osmotic pressures extended the range of previous force measurements demonstrating a new fluctuation enhanced force regime). The remarkable feature of this motional enhancement is a quadrupling of the range of direct forces. These observations are being connected with the most sophisticated physical theories of liquid-crystal assembly as well as with immediate questions how DNA fits within the confines of small spaces such as viral capsids. Quantitative measurement of the amount of water released upon the binding o various proteins to DNA shows qualitative differences in dehydration when the protein/DNA association is specific rather than non-specific. There is an apparent connection between these changes in molecular hydration and the powerful "hydration forces" measured between large molecules brought into contact. We have finally enjoyed clear progress on a major theoretical question, the annoying, "vapor pressure paradox," wherein membranes are known to imbibe less water from a vapor than from a liquid solution of the same chemical potential as water. According to our formulation, a surface that suppresse molecular motion will exert its repression very far into a medium (even cellular dimensions) and will stop molecular expansion. Within weeks of ou initial formulation, experiments suggested to another laboratory showed the kind of surface perturbation that was predicted. Other labs are now showin the generality of the phenomenon we have identified. The consequence of this work is that we must ask whether the solution properties of bilayer membranes, or ~semi-flexible~ molecules such as DNA, are the same within th micron-wide confines as they are in the centimeter-size vessels in which they are normally studied.

这项工作的主题是发展一个有用的，准确的科学力量 来组织生物分子。 为此，我们集中力量， 测量蛋白质、DNA双螺旋和多糖之间的作用力。 用于直接力测量的渗透应力方法正在取得胜利 在世界各地广泛使用。我们的LSB主页包含一个~生活 渗透应力数据和校准曲线手册。记录显示 我们的主页有时会被访问， 分钟 关于DNA力的最新研究将渗透压与SAXS结合起来， 偏光显微镜使用同步辐射以及普通x射线 射线源已经显示出几种不同形式的分子堆积， 包括一个以极大的运动自由度为特征的运动阶段 （低渗透压下的透析实验扩展了 先前的力测量表明一种新的波动增强力 制度）。这种运动增强的显著特征是 使直接力的范围扩大四倍。 这些观察结果被 与最复杂的液晶物理理论有关 组装以及直接的问题，DNA如何适应在 病毒衣壳等小空间的限制。 定量测量结合时释放的水的量。 各种蛋白质到DNA显示出质的差异脱水时， 蛋白质/DNA的结合是特异性的而不是非特异性的。 有 分子水合作用的这些变化与 强大的“水化力”测量大分子之间的带入 contact. 我们终于在一个重大的理论问题上取得了明显的进展， 令人讨厌的“蒸汽压悖论”，其中膜已知会吸收 蒸汽中的水比同一化学物质的液体溶液中的水少 潜力如水。 根据我们的公式，一个表面， 分子运动将把它的抑制作用施加到介质（甚至 细胞尺寸）并将停止分子膨胀。 在你出生后的几周内 最初的配方，实验建议另一个实验室显示， 一种被预测的表面扰动。 其他实验室现在显示 我们所发现的现象的普遍性。 的后果 这项工作是，我们必须问，是否双层的溶液性质， 膜，或半柔性分子，如DNA，在细胞内是相同的。 微米宽的范围，因为他们是在厘米大小的船只， 他们通常被研究。