X-RAY AND CHEMICAL STUDIES OF METALLOPORPHYRINS

金属卟啉的 X 射线和化学研究

• 批准号: 2415137
• 负责人: W. ROBERT SCHEIDT
• 金额: $ 28.89万
• 依托单位: UNIVERSITY OF NOTRE DAME
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-05-01 至 2000-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2415137
• 关键词: Mossbauer spectrometry; X ray crystallography; electron spin resonance spectroscopy; hemoprotein structure; metalloporphyrins; porphyrin structure; quantum chemistry; stereochemistry

DESCRIPTION: This is a competitive renewal of R01 GM38401-24 to continue Dr. Scheidt's long standing leadership role in the synthesis and characterization of new metalloporphyrin compounds. The work emphasizes, but is not limited to, the iron porphyrinate compounds and their derivatives. Most of the classes of compounds that are proposed for study are related to the goal of developing a detailed understanding of hemoproteins and the chemistry of their prosthetic groups. A second major area of focus is on the class of porphyrinate derivatives which are related to the prosthetic groups central to photosynthetic reactions. The primary method to be employed is three-dimensional X-ray crystal structure determination, with the goal of defining the molecular structures and various detailed functional aspects of metalloporphyrin stereochemistry. Through an extensive list of world-class collaborators, other methodologies to be applied to this quest include the characterization of magnetic properties by bulk temperature-dependent susceptibility and electron paramagnetic resonance (EPR) measurements, Mossbauer spectroscopy, vibrational and UV-vis-NIR spectroscopy, electrochemical properties, and molecular mechanics calculations. The overall stated research objectives are to achieve a synergistic understanding of the structural and physical properties of metalloporphyrins, particularly as these relationships pertain to an understanding of hemoprotein-based biological processes. The general paths include establishing possible stereochemical features of a metalloporphyrin group in its biological environment and modeling specific prosthetic group behavior of selected hemoproteins through theoretical calculations. Such studies are expected to provide understanding of how protein structures could modulate metalloporphyrin geometry and how a wide variety of biological processes can be carried out by nature by using the same fundamental iron protoporphyrin IX prosthetic group. Iron porphyrinates to be studied include synthetic analogs of bis(istidine)-ligated cytochromes b and c to examine how features such as axial ligand orientation affect their electronic structure and oxidation-reduction properties. Another significant research objective is the exploration of electronic interactions in metalloporphyrins; detailed studies will examine coupling in systems with potential intra- and/or intermolecular pathways. Included in such studies are species with oxidized or reduced porphyrin cores in which pi-radical spin-coupling is significant. These species are important to understanding catalytically important intermediates of high-valent hemoprotein systems such as the catalases, peroxidases, and cytochromes P-450. Other systems with electronic coupling interactions to be explored include systems with the coupled metal ion separated in well-defined ways through bridging ligands or porphyrin-porphyrin pi-pi interaction.

描述：这是R 01 GM 38401 -24的竞争性续订，以继续 博士Scheidt在综合和 新金属卟啉化合物的表征。 工作强调， 但不限于，铁卟啉化合物和它们的 衍生物. 大多数种类的化合物，建议用于 研究的目标是详细了解 血红素蛋白及其辅基的化学性质。 第二 主要关注的领域是卟啉衍生物类， 与光合作用的核心辅基有关 反应. 采用的主要方法是三维X射线 晶体结构测定，目的是确定分子 金属卟啉的结构和各种详细的功能方面 立体化学通过广泛的世界级合作者名单， 其他适用于这一探索的方法包括 通过体温度依赖性表征磁性 磁化率和电子顺磁共振（EPR）测量， 穆斯堡尔光谱、振动光谱和紫外可见近红外光谱， 电化学性质和分子力学计算。 总体研究目标是实现协同 了解的结构和物理性质的 金属卟啉，特别是因为这些关系涉及到一个 了解基于血红蛋白的生物过程。 总 途径包括建立可能的立体化学特征， 金属卟啉基团在生物环境中的作用及其模拟 特定辅基行为的选择血红素蛋白，通过 理论计算。 预计这些研究将提供 了解蛋白质结构如何调节金属卟啉 几何学以及各种各样的生物过程是如何 通过使用相同的基本铁原卟啉IX 辅基 研究的铁卟啉盐包括合成的铁卟啉盐。 类似物的双（二氢吡啶）连接的细胞色素B和C，以检查如何 诸如轴向配体取向的特征影响它们的电子 结构和氧化还原性能。 另一个重要 研究目标是探索电子相互作用， 金属卟啉;详细的研究将检查耦合系统 具有潜在的分子内和/或分子间途径。 这些研究包括具有氧化或还原卟啉的物种 其中π自由基自旋耦合是显著的核。 这些物种 对于理解催化剂的重要中间体很重要， 高价血红素蛋白系统，如过氧化氢酶、过氧化物酶和 细胞色素P-450。 具有电子耦合相互作用的其他系统 将被探索的系统包括具有分离的偶联金属离子的系统， 通过桥连配体或卟啉-卟啉π-π 互动