X-RAY AND CHEMICAL STUDIES OF METALLOPORPHYRINS

金属卟啉的 X 射线和化学研究

• 批准号: 2179316
• 负责人: W. ROBERT SCHEIDT
• 金额: $ 26.45万
• 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 1996-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2179316
• 关键词: Mossbauer spectrometry; X ray crystallography; chemical stability; chemical substitution; chemical synthesis; copper; electron spin resonance spectroscopy; electron transport; electronic spectra; free radical oxygen; hemoprotein; hemoprotein structure; imidazole; intermolecular interaction; ionic bond; iron; ligands; metalloporphyrins; molecular energy level; molecular orbital; nickel; nitrites; oxidation reduction reaction; porphyrin structure; pyridine; quantum chemistry; stereochemistry; sulfites; thioether

The synthesis and characterization of a variety of new metalloporphyrin compounds is proposed. The work will emphasize, but will not be limited to, iron porphyrinate derivatives. Most classes of compounds proposed for study are related to hemoprotein derivatives, which carry out a wide range of biological functions including oxygen utilization and transport, electron transport, drug metabolism and other enzymatic processes. Another class of derivatives are related to species of photosynthetic reactions. The methods of three-dimensional X-ray crystal structure determination will be applied to define molecular structures and various detailed aspects of metalloporphyrin stereochemistry. Other methodologies to be applied, as appropriate, include characterization of magnetic properties by bulk temperature-dependent susceptibility and electron paramagnetic resonance (EPR) measurements, Mossbauer, vibrational and UV-vis spectroscopy, and electrochemical properties. The research objectives, stated in the broadest terms, are to achieve a synthesis of the structural and physical properties of metalloporphyrins, particularly as these relationships pertain to an understanding of hemoprotein-based biological processes. In part, this will be accomplished by establishing possible stereochemical features of a metalloporphyrin group and its biological environment and to model specific prosthetic group behavior of selected hemoproteins. 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 with the same fundamental iron protoporphyrin IX unit. Iron porphyrinates to be studied include synthetic analogues of bis(histidine)-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 eta-radical spin-coupling is significant. These species are important to understanding catalytically important intermediates of high-valent hemoprotein systems such as catalases and peroxidases. Other systems with electronic coupling interactions to be explored include systems with the coupled metal ions separated in well-defined ways (bridging ligands or electrostatic interactions).

几种新型金属卟啉的合成与表征 化合物提出。 这项工作将强调，但不会受到限制 铁卟啉衍生物。 大多数类别的化合物建议用于 研究涉及血红素蛋白衍生物，其进行了广泛 包括氧的利用和运输， 电子传递、药物代谢和其他酶促过程。 另一 一类衍生物与光合反应的种类有关。 三维X射线晶体结构测定方法将 应用于定义分子结构和各种详细的方面， 金属卟啉立体化学 将采用的其他方法，如 适当的，包括按体积表征磁性 变温磁化率和电子顺磁共振 (EPR)测量，穆斯堡尔，振动和紫外可见光谱，和 电化学性能 研究目的，在 最广泛的术语，是实现结构和物理的综合， 金属卟啉的性质，特别是这些关系 与理解基于血蛋白的生物过程有关。 在 部分，这将通过建立可能的立体化学来实现。 金属卟啉基团的特征及其生物环境， 模拟所选血红素蛋白的特定辅基行为。 等 这些研究有望帮助我们理解蛋白质结构 可以调节金属卟啉的几何形状， 生物过程可以用相同的基本铁来进行， 原卟啉IX单位。 研究的铁卟啉盐包括合成的铁卟啉盐。 双（组氨酸）连接的细胞色素B和C的类似物，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。 另一个重要的研究目标 是探索金属卟啉中的电子相互作用; 详细的研究将检查系统中的耦合， 和/或分子间途径。 这些研究中包括的物种 氧化或还原的卟啉核，其中η-自由基自旋偶合 显著 这些物种对于理解催化 高价血红素蛋白系统的重要中间体， 过氧化氢酶和过氧化物酶。 其他具有电子耦合的系统 待探索的相互作用包括具有耦合金属离子的系统 以明确的方式分离（桥接配体或静电 互动）。