HYDROGEN BONDING IN METALLOPORPHYRIN REACTIONS

金属卟啉反应中的氢键

• 批准号: 3152022
• 负责人: DWIGHT A SWEIGART
• 金额: $ 6.62万
• 依托单位: BROWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1983
• 资助国家: 美国
• 起止时间: 1983-07-01 至 1986-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3152022
• 关键词: catalase; chemical reaction; cobalt; cytochromes; electrochemistry; hemoglobin; hemoprotein; hydrogen bond; imidazole; ligands; metalloporphyrins; myoglobin; oxidation reduction reaction; peroxidases; ruthenium; thermodynamics

The aim of the proposed research is to quantitatively establish the effect of hydrogen bonding on the kinetics, thermodynamics, and redox properties of metalloporphyrin reactions. The hydrogen-bonding is of two types: to an axially coordinated ligand (distal effect) and from an axially coordinated ligand (proximal effect). Preliminary experiments suggest that distal hydrogen-bonding can greatly influence the kinetics and thermodynamics of ligand dissociation and association when the coordinated ligand is anionic. One of the reactions to be investigated is Fe(porphyrin)X + 2 RIm greater than Fe(porphyrin)(RIm)2+, X-, where X is one of a variety of anionic ligands and RIm is an imidazole. This reaction goes through the unstable monoimidazole intermediate Fe(porphyrin)(RIm)X which is a model for a number of hemoproteins. The influence of hydrogen-bonding from RIm and to X- in Fe(porphyrin)(RIm)X will be thoroughly investigated by rapid reaction techniques (low temperature stopped-flow, NMR) and electrochemical techniques (stationary electrode voltammetry, polarography). Several other metalloprophyrins, principally those of cobalt and ruthenium containing coordinated dioxygen, will also be investigated. The hydrogen-bonding to be studied can be from the solvent, nucleophile, or other external source to the distal ligand or from coordinated imidazole to solvent or other basic species. The elucidation of the importance of hydrogen-bonding on the ligand association and dissociation rates, reaction thermodynamics, and metalloporphyrin redox potentials will provide a basis for understanding the importance of these effects in reactions mediated by hemoproteins such as hemoglobin, myoglobin, catalases, peroxidases, and cytochromes.

拟议研究的目的是定量确定效果 动力学，热力学和氧化还原特性上的氢键 金属卟啉反应。 氢键有两种类型： 轴向协调的配体（远端效应）和轴向 配体（近端效应）。 初步实验表明 远端氢键可以极大地影响动力学和 协调时配体解离和关联的热力学 配体是阴离子。 要研究的反应之一是 fe（卟啉）x + 2边缘大于fe（卟啉）（rim）2+，x-，其中x为 各种阴离子配体和边缘之一是咪唑。 这个反应 穿过不稳定的单咪唑中间Fe（卟啉）（RIM）x 这是多种血蛋白的模型。 影响 从边缘到x-的氢键（卟啉）（轮辋）x为x 通过快速反应技术进行了彻底研究（低温 停止流，NMR）和电化学技术（固定电极 伏安法，光学学）。 其他几种金属prophyrins，主要是 钴和含有协调二氧化物的钴和芳族的那些也将是 调查。 要研究的氢键可以来自溶剂， 亲核试剂或远端配体的其他外部来源或来自 协调咪唑到溶剂或其他基本物种。 阐明 氢键对配体关联的重要性和 解离速率，反应热力学和金属卟啉氧化还原 潜力将为理解这些重要性提供基础 在由血红蛋白等血红蛋白介导的反应中的作用， 肌红蛋白，催化酶，过氧化物酶和细胞色素。