Substrate Properties and the Conformational State of Polyelectrolytes

底物性质和聚电解质的构象状态

• 批准号: 8158392
• 负责人: EMILIOS K DIMITRIADIS
• 金额: $ 4.06万
• 依托单位: NATIONAL INSTITUTE OF BIOMEDICAL IMAGING AND BIOENGINEERING
• 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/8158392
• 关键词: Molecular Conformation; Property

DNA and proteins belong to the class of polyelectrolytes, polymer molecules that, in solution, carry charge. We study primarily two very different such molecules, DNA and the glycoprotein aggrecan, a major structural component of articular cartilage. Their conformational states are strongly influenced by the ionic environment and multivalent ions affect intra- and intermolecular interactions and hence the conformational state of such molecules. In addition these molecules function in close proximity to organized, charged surfaces such as lipid bilayers and collagen matrices. We use a combination of techniques to study the conformational states and intermolecular interactions of the molecules adsorbed to positively and negatively charged surfaces. Atomic force microscopy (AFM) is used to visualize and analyze the conformations of the molecular assemblies at a single molecule level, while dynamic light scattering (DSL) and quartz crystal microbalance(QCM) are employed to estimate the changes in hydration and the size distribution in solution. During the past few months we studied the interactions of aggrecan with charged surfaces. We found that on positively charged surfaces the GAG chains of the aggrecan molecules were distinguishable, and their average dimensions were practically unaffected by the presence of salt ions. With increasing aggrecan concentration they formed clusters, and at higher concentrations they formed a continuous monolayer of conforming molecules. On negatively charged mica, the extent of aggrecan adsorption varied with salt composition.

DNA和蛋白质属于聚电解质类，即在溶液中携带电荷的聚合物分子。我们主要研究两种非常不同的分子，DNA和糖蛋白聚集蛋白聚糖，关节软骨的主要结构组成部分。它们的构象状态受到离子环境的强烈影响，多价离子影响分子内和分子间的相互作用，因此影响这些分子的构象状态。此外，这些分子的功能非常接近有组织的，带电的表面，如脂质双层和胶原蛋白基质。我们使用的技术相结合，以研究的构象状态和分子间的相互作用的分子吸附到带正电荷和负电荷的表面。原子力显微镜（AFM）用于在单分子水平上观察和分析分子组装体的构象，而动态光散射（DSL）和石英晶体微天平（QCM）用于估计水化的变化和溶液中的尺寸分布。在过去的几个月里，我们研究了聚集蛋白聚糖与带电表面的相互作用。我们发现，在带正电荷的表面上的聚集蛋白聚糖分子的GAG链是可区分的，并且它们的平均尺寸几乎不受盐离子的存在的影响。 随着聚集蛋白聚糖浓度的增加，它们形成簇，并且在更高的浓度下，它们形成一致分子的连续单层。 在带负电荷的云母上，聚集蛋白聚糖的吸附程度随盐的组成而变化。