CONFORMATION AND DYNAMICS OF POLYSACCHARIDES

本项目旨在探索 化学结构和分子构象和动力学 碳水化合物大分子 这些广泛分布的化合物是 所有生命系统的基本结构和能量储存组件。 它们的功能在真核细胞表面越来越被认识 其中，由于它们的拓扑和构象能力， 多样性，它们负责储存和表达 控制诸如血型等现象的生物信息， 凝血链的调节、同种异体移植物的接受或 排斥、生长因子的接受和调节以及细胞-细胞 识别和粘附。 细菌荚膜多糖在 这些生物作为一个保护壳，并管理水的活动， 细胞外表面和细胞的粘附特性。 这 胞外多糖在许多细胞中含有抗原决定簇， 病原菌和无细胞样品用作疫苗。 化学结构和大分子构象的问题是 采用计算机建模和定量分析相结合的方法， 稀溶液性质的实验表征。 因为 重点是高分子聚合物，它必然表现出构象 即使当它们采用相对有序的螺旋构象时， 在计算机建模中必须采用统计力学的方法 建立一个定量的和概念上准确的联系， 化学结构和可观察的物理性质。 可观察 感兴趣的特征是用最少的近似计算的特征 从统计学理论。 重点是全局构象特征 可通过光散射和流体动力学测量获得， 通过适当的NMR测量可获得构象特征。 这些系统的动力学和平衡性质是根据 调查 13 C NMR弛豫测量用于探测 频谱的构象运动，这些意见是 用真实的计算机从分子的角度来解释 水溶性低聚糖的分子动力学模拟。

This project is designed to explore fundamental relationships between the chemical structure and the molecular conformation and dynamics of carbohydrate macromolecules. These widely distributed compounds are essential structural and energy storage components of all living systems. Their function is increasingly recognized at eukaryotic cell surfaces where, by virtue of their capacity for topological and conformational diversity, they are responsible for the storage and expression of biological information that governs such phenomena as blood type, regulation of the blood coagulation chain, allograft acceptance or rejection, growth factor reception and regulation, and cell-cell recognition and adhesion. Bacterial capsular polysaccharides function in these organisms as a protective shell and govern the activity of water at the external cell surface and the adhesive properties of the cell. This extracellular polysaccharide contains an antigenic determinant in many pathogenic bacteria, and cell-free samples are used as vaccines. The question of chemical structure and macromolecular conformation is approached using a combination of computer modeling and quantitative experimental characterization of the dilute solution properties. Because the emphasis is on high polymers, which necessarily exhibit conformational variability even when they adopt relatively ordered helical conformations, the methods of statistical mechanics must be used in the computer modeling to make a quantitative and conceptually accurate connection between chemical structure and observable physical properties. Observable characteristics of interest are those computed with fewest approximations from the statistical theory. Emphasis is on global conformational features obtainable from light scattering and hydrodynamic measurements and on local conformational features accessible from appropriate NMR measurements. Dynamic as well as equilibrium properties of these systems are under investigation. 13C NMR relaxation measurements are used to probe the frequency spectrum of conformational motions, and these observations are interpreted in detailed molecular terms using realistic computer simulations of the molecular dynamics of aqueous oligosaccharides.