X-RAY AND CHEMICAL STUDIES OF METALLOPORPHYRINS

金属卟啉的 X 射线和化学研究

• 批准号: 2910070
• 负责人: W. ROBERT SCHEIDT
• 金额: $ 30.29万
• 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/2910070
• 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R01 GM38401-24的竞争性续订，继续 Scheidt博士在合成和研究中的长期领导作用 新型金属卟啉化合物的表征。这部作品强调， 但不限于，铁的卟啉化合物及其 衍生品。所建议的大多数化合物类别 学习都是与制定目标相关的详细理解 血球蛋白及其假体基团的化学。一秒钟 主要关注的领域是一类卟啉衍生物，它 与光合作用中心的修复基团有关 反应。采用的主要方法是三维X射线 晶体结构测定，目标是确定分子 金属卟啉的结构和各种详细的功能 立体化学。通过一系列世界级的合作者， 其他将应用于这一任务的方法包括 体温变化对磁性能的表征 磁化率和电子顺磁共振(EPR)测量， 穆斯堡尔光谱、振动光谱和UV-Vis-NIR光谱， 电化学性质和分子力学计算。 总体陈述的研究目标是实现协同效应 了解材料的结构和物理性质 金属卟啉，特别是当这些关系与 了解以血红蛋白为基础的生物过程。这位将军 途径包括建立一种可能的立体化学特征 金属卟啉基团的生物环境及其模拟 通过选择的血液蛋白的特定假体群体行为 理论计算。这类研究有望提供 了解蛋白质结构如何调节金属卟啉 几何学和如何进行各种各样的生物过程 通过使用相同的基本铁原卟啉IX 修复组。将研究的卟啉铁酸盐包括合成的 双(异硫氨酸)连接的细胞色素b和c的类似物 轴向配基取向等特征会影响其电子结构 结构和氧化还原性能。另一个重要的 研究目标是探索电子相互作用在 金属卟啉；详细研究将检查系统中的耦合 具有潜在的分子内和/或分子间途径。 这类研究包括氧化或还原的卟啉物种。 其中pi-自由基自旋耦合显著的核心。这些物种 对于理解具有催化作用的重要中间体很重要 高价血红蛋白系统，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 要探索的系统包括耦合的金属离子在 通过桥联配体或卟啉-卟啉pi-pi的明确方式 互动。