DEVELOPMENT OF 2D AND 3D NMR FOR STUDIES OF BIOMOLECULES

该项目的主要目标是开发新的高分辨率 核磁共振（NMR）方法用于研究 生物分子如蛋白质和核酸的结构和动力学。 核磁共振光谱学已经成为研究 溶液中的生物分子，由于其能够提供详细的 在原子水平上的信息NMR光谱可以在多大程度上被 用于生物分子的三维结构测定， 系统中分子间相互作用的研究， 药物/受体、酶/底物和抗体/抗原复合物，以及 分子碎片动力学的表征，将取决于 操纵系统以产生EM所需信息的能力。 的 生物核磁共振在过去十年中做出了巨大的贡献 在生物分子和生物物理过程的调查是由于 在很大程度上是为了继续开发新的或改进的技术， 从感兴趣的系统中提取有用的数据。 任何核磁共振研究的先决条件是共振的分配 与目标分子中的单个原子核相关联。 一个最 目前用于共振分配的有效实验是基于 基于各向同性混合的原理。 尽管如此， 实验中，他们还没有得到很好的理论特征。 一个目的 提出的研究是一个详细的分析和发展的各种 各向同性混合实验方面，特别是，发展 采用多频率照射的新方案， 效率 此外，新的实验采用各向同性混合， 将探索异质相干转移。 在新的核磁共振技术的发展及其分析中， 由于这些特征，通常会做出简化的假设。 然而，在这方面， 在最近的一些实验中，特别是那些长时间使用 在射频辐射的周期内，有必要进行更多的 严格的分析，其中包括NMR弛豫现象的影响。 在新的开发过程中考虑弛豫过程是至关重要的。 旨在分离松弛和连贯效应的实验 转移 本提案的主要目标之一是推导出 用于将弛豫效应包括到NMR模拟中的方便的形式主义， 并将其用于改进的各向同性混合的开发， 相关技术。 虽然核磁共振是获得详细信息的首选方法， 在溶液中生物分子的物理研究中，不幸的是， 相对不敏感的技术。 建议调查 有前途的计划，以提高灵敏度的各种，重要的 技术，如各向同性混合，异向相关方法， 弛豫时间测量 从理论上讲，新的实验 所开发的可将所需的测量时间减少一半。 生物分子系统中的动力学过程通常在以下方面起关键作用： 生物学功能，因此具有合适的方法非常重要 来描述这些现象。 核磁共振光谱是一种非常强大的 获得分子动力学详细信息的工具 片段 该提案的一个重要目的是， 从理论上证明了多重量子技术的有效性 研究化学重组过程。 另一个主要目标是 开发有助于测量异质性的技术 松弛率 这些数据将是非常宝贵的， 生物分子如蛋白质和核酸的结构研究。

The major goal of this project is the development of new, high resolution nuclear magnetic resonance (NMR) methodologies for use in studies of the structure and dynamics of biomolecules such as proteins and nucleic acids. NMR spectroscopy has become an extremely powerful tool for the study of biomolecules in solution, due to its ability to provide detailed information at an atomic level The extent to which NMR spectroscopy can be exploited for three-dimensional structure determinations of biomolecules, the investigation of intermolecular interactions in systems such as drug/receptor, enzyme/substrate and antibody/antigen complexes, and the characterization of the dynamics of molecular fragments, will depend on the ability to manipulate the system to yield EM desired information. The enormous contribution that biological NMR has made during the last decade in the investigation of biomolecules and biophysical processes is due largely to the continuing development of new or improved techniques for extracting useful data from the systems of interest. A prerequisite step in any NMR study is the assignment of resonances to individual nuclei in the molecule of interest. One of the most efficient experiments currently in use for resonance assignment is based on the principle of isotropic mixing. Despite the popularity of such experiments, they have not been well characterized theoretically. One aim of the proposed research is a detailed analysis and development of various aspects of isotropic mixing experiments, in particular, the development of novel schemes employing multiple frequency irradiation to improve the efficiency. Also, new experiments employing isotropic mixing for heteronuclear coherence transfer will be explored. In the development of new NMR techniques and the analysis of their characteristics, it is common to make simplifying assumptions. However, in some of the most recent experiments, especially those employing long periods of radio-frequency irradiation, it is necessary to conduct a more rigorous analysis which includes the effects of NMR relaxation phenomena. It is vital to consider relaxation processes in the development of new experiments designed to separate the effects of relaxation and coherence transfer. One of the major goals in this proposal is to derive a convenient formalism for including relaxation effects into NMR simulations, and to use this for the development of improved isotropic mixing and related techniques. While NMR is the method of choice for obtaining detailed information in physical studies of biomolecules in solution, it unfortunately is a comparatively insensitive technique. It is proposed to investigate promising schemes for improving the sensitivity of various, important techniques such as isotropic mixing, heteronuclear correlation methods and relaxation time measurements. Theoretically, the new experiments to be developed can reduce the required measuring time in half. Dynamical processes in biomolecular systems often play a key role in biological function, and thus it is very important to have suitable methods for characterizing such phenomena. NMR spectroscopy is a very powerful tool for obtaining detailed information on the dynamics of molecular fragments. One important aim of this proposal is to characterize theoretically and demonstrate the usefulness of multiple quantum techniques for studying chemical reorganization processes. Another major goal is to develop techniques which will facilitate the measurement of heteronuclear relaxation rates. Such data would be invaluable for use in functional and structural studies of biomolecules such as proteins and nucleic acids.