Carbon-13 Magnetic Resonance- Methods and Theory

碳 13 磁共振 - 方法和理论

• 批准号: 6610546
• 负责人: David Morris Grant
• 金额: $ 25.48万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-06-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6610546
• 关键词: bioengineering /biomedical engineering; biomedical equipment development; biophysics; carbon; chemical models; chemical structure; conformation; hydrogen bond; intermolecular interaction; liquid crystal; method development; molecular dynamics; monoterpenes; nitrogen; nitrogenous heterocyclic compound; nuclear magnetic resonance spectroscopy; nucleobase; peptide structure; quantum chemistry; stable isotope; structural biology; tannins

DESCRIPTION (provided by applicant): This research project involves the continued development (now entering its 5th decade) of basic methods and theory for advancing the use of NMR techniques in relevant biomedical areas for detecting less receptive nuclei with special emphasis placed on 13C and 15N. Earlier work stressed the chemical shift structure correlations of liquid samples and more recently these concepts are being developed in the shielding tensor. The 3D aspects of 13C and 15N shielding tensors and their applications to biological systems are well documented in the publications of our laboratory. Further developments of spectroscopic techniques and their correlation with theory continue to be significant aspects of this proposal. Major developments have been made in experimental techniques for determining shielding tensors on either powders or single crystals and their orientation on the molecular frame. Shift tensors, with their three principal values and three angular orientations, provide information on the symmetry and three dimensional structure of molecules not obtainable from isotropic shifts in liquids. Finished tensor work on aromatic systems and sugars is now being extended to relatively large natural products, nitrogen heterocycles, nucleosides, nucleotides, peptides and their related polymeric oligomers. Capabilities now exist to index and thoroughly analyze powdered samples containing dozens of non-equivalent carbons. Furthermore, theoretical methods have improved to the point where it is possible to discuss structural effects on 13C chemical shift changes under 2.5 ppm for neutral molecules with limited charge polarization present. Recent advances in the Utah NMR laboratory on Ewald potentials reveals a very promising way to treat long range charge polarization mechanisms that can also affect chemical shift components by as much as 50 ppm. This charge polarization mechanism is strongly perturbed by electrostatic fields characterized by long range electrostatic forces that give rise to shift perturbations in highly polar molecules. Calculating fields from interactions of monopolar arrays has long been known to require lattice sums that converge very slowly over long distances. New approaches to this problem are proposed in this renewal. Hence, the work at the Utah laboratory will continue to develop experimental and theoretical methods to be employed in the study of shift tensors in peptides, protein conformational analysis, correlations between biochemical structure and shift tensor data in biological complexes, natural products, and hydrogen bonded interactions.

描述（由申请人提供）：该研究项目涉及基本方法和理论的持续开发（现在进入其第5个十年），用于推进在相关生物医学领域使用NMR技术，以检测较少接受的核，并在13C和15N上进行了特殊重点。较早的工作强调了液体样品的化学位移结构相关性，最近这些概念正在屏蔽张量中开发。在我们的实验室出版物中，有充分的记录记录了13C和15N屏蔽张量及其对生物系统的应用的3D方面。光谱技术的进一步发展及其与理论的相关性仍然是该提案的重要方面。在实验技术中已经做出了重大发展，以确定粉末或单晶上的屏蔽张量及其在分子框架上的方向。 移位张量及其三个主值和三个角度取向，提供了有关分子的对称性和三维结构的信息，这些分子无法从液体中的各向同性移位中获得。目前，在芳族系统和糖上完成的张量工作正在扩展到相对较大的天然产物，氮杂环，核苷，核苷酸，肽及其相关的聚合物低聚物。现在存在索引的功能，并彻底分析包含数十个非等效碳的粉末状样品。此外，理论方法已改进到可以在2.5 ppm以下的13c化学位移变化的中性分子中讨论具有有限电荷极化的中性分子的结构效应。犹他州NMR实验室在Ewald电位上的最新进展揭示了一种非常有希望的处理远距离电荷极化机制的方法，该方法也可以影响化学位移成分高达50 ppm。这种电荷极化机制受到静电场的强烈扰动，其特征在于远程静电力，从而导致高度极性分子的偏移扰动。长期以来，已知从单极阵列的相互作用来计算场需要的晶格总和在长距离内收敛非常缓慢。在此续约中提出了解决此问题的新方法。 因此，犹他州实验室的工作将继续开发用于研究肽中的转移张量，蛋白质构象分析，生物化学结构之间的相关性和生物学结构之间的相关性和生物学复合物，天然产物和氢键相互作用的相关性。