X RAY AND CHEMICAL STUDIES OF METALLOPORHYRINS

金属卟啉的 X 射线和化学研究

• 批准号: 6385678
• 负责人: W. ROBERT SCHEIDT
• 金额: $ 32.64万
• 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 2004-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6385678
• 关键词: Mossbauer spectrometry; X ray crystallography; chemical property; chemical structure; chemical synthesis; electron spin resonance spectroscopy; hemoprotein structure; infrared spectrometry; intermolecular interaction; iron compounds; metalloporphyrins; porphyrin structure; quantum chemistry; stereochemistry; ultraviolet spectrometry

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 developing an understanding of hemoprotein derivatives, which carry out a wide range of biological functions including oxygen utilization and transport, NO-based signaling, electron transport, drug metabolism and a variety of other enzymatic processes. Another class of derivatives is related to species important to 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. Mssbauer spectroscopy, vibrational and UV-vis-near-IR spectroscopy, electrochemical properties, and molecular mechanics calculations. 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 in 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 pi-radical spin coupling is significant.

提出了多种新型金属卟啉化合物的合成和表征。 这项工作将重点关注但不限于卟啉酸铁衍生物。 提议研究的大多数化合物类别都与了解血红素蛋白衍生物有关，血红素蛋白衍生物具有广泛的生物功能，包括氧利用和运输、基于一氧化氮的信号传导、电子运输、药物代谢和各种其他酶促过程。 另一类衍生物与对光合作用反应重要的物种有关。 三维X射线晶体结构测定方法将用于定义分子结构和金属卟啉立体化学的各个细节方面。 酌情应用的其他方法包括通过整体温度相关磁化率和电子顺磁共振（EPR）测量来表征磁特性。 穆斯堡尔光谱、振动和紫外-可见-近红外光谱、电化学性质和分子力学计算。从最广泛的角度来说，研究目标是实现金属卟啉的结构和物理特性的综合，特别是因为这些关系涉及对基于血红素蛋白的生物过程的理解。 在某种程度上，这将通过在其生物环境中建立金属卟啉基团可能的立体化学特征并模拟选定血红蛋白的特定辅基行为来实现。 此类研究预计将有助于了解蛋白质结构如何调节金属卟啉几何形状，以及如何使用相同的基本铁原卟啉 IX 单元进行多种生物过程。 待研究的铁卟啉包括双（组氨酸）连接的细胞色素 b 和 c 的合成类似物，以研究轴向配体方向等特征如何影响其电子结构和氧化还原性质。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具有潜在的分子内和/或分子间途径的耦合。 此类研究包括具有氧化或还原卟啉核心的物种，其中π自由基自旋耦合很重要。