Heme/Copper and Heme/Nonheme Iron O(2) and NO Reactivity

项目摘要（最多30行） 长期的研究目标是设计、合成和研究模型化合物系统， 可以帮助阐明结构的基本方面，金属连接，光谱学和相关的反应性， 血红素-铜氧化酶（HCOs）和一氧化氮还原酶（NORs）所利用的化学。这些 进化上相关的酶在需氧和厌氧生物的生物能量学中起关键作用， 并且共同具有血红素/M（M =铜或非血红素铁）活性位点， 氧气（O2）或一氧化氮（NO，一氧化氮）。这项研究可能有助于 更好地了解酶的结构和机制，并提供基本的见解， 氧气和NO的生物处理，氮氧化物的化学和生物化学，以及 解决与环境中的氮氧化物有关的问题。具体目标包括：（1） 血红素-过氧-铜配合物，新的质子化和新的低自旋衍生物和阐明其过氧- 连接性和电子结构，（2）已经很好地促进了还原O-O断裂的研究 特征血红素-过氧-铜络合物系统，并阐明这一过程的关键因素， 包括化学或生物化学系统中“氧活化”的关键方面，（3）设计新的 具有连接的苯酚-咪唑部分的铜的配体，以阐明这样的基团如何可以 O-O裂解化学的一部分，即，HCO功能。其他新的双核配体血红素/铜将是 设计用于测试酶His-Tyr交联在自然界中如何形成，（4）血红素/NO/O2的研究 配位化学-包括二亚硝酰血红素络合物的表观可逆形成， 模拟血红素蛋白的作用，如发生在酶NO-双加氧酶，（5）新的研究方法 血红素/非血红素二铁和血红素/铜复合物的NO还原酶活性，包括设计了一些 双金属化学体系，用于系统地研究它们还原偶联两个NO 分子产生一氧化二氮（N2 O），和（6）金属结合动力学的详细调查， 血红素、血红素/铜和血红素/非血红素二铁络合物中的一氧化氮-这种光引发的 反应可以提供动力学，热力学和金属的详细了解 这些小分子在与血红素/非血红素金属位点的相互作用中的偏好/迁移， HCO和NOR生物化学。

Project Summary (30 lines maximum) The long-term research objective is to design, synthesize and investigate model compound systems which can help elucidate fundamental aspects of structure, metal ligation, spectroscopy and reactivity relevant to the chemistry utilized by heme-copper oxidases (HCOs) and nitric oxide reductases (NORs). These evolutionarily related enzymes play critical roles in the bioenergetics of aerobic and anaerobic organisms, and have in common a heme/M (M = copper or non-heme iron) active site which reductively cleaves dioxygen (O2) or nitric oxide (NO, nitrogen monoxide), respectively. The research proposed can contribute to a better understanding of enzyme structure and mechanism and provide fundamental insights into the biological processing of dioxygen and NO, the chemistry and biochemistry of nitrogen oxides, as well as address issues related to nitrogen oxides in the environment. Specific aims include (1) the characterization of heme-peroxo-Cu complexes, new protonated and new low-spin derivatives and elucidation of their peroxo- connectivity and electronic structures, (2) the study of reductive O-O cleavage promoted by already well characterized heme-peroxo-Cu complex systems, and elucidation of the factors crucial for this process, comprising a critical aspect of 'oxygen activation' in chemical or biochemical systems, (3) the design of new ligands for copper which possess a linked phenol-imidazole moiety, to elucidate how such a group may take part in O-O cleavage chemistry, i.e., HCO function. Other new binucleating ligands for heme/Cu will be designed to test how in nature the enzyme His-Tyr crosslink might form, (4) investigation of heme/NO/O2 coordination chemistry - including the apparent reversible formation of a dinitrosyl heme complex and modeling heme protein actions such as occur in enzyme NO-dioxygenases, (5) new approaches to the study of NO reductase activity of heme/non-heme diiron and heme/Cu complexes, including design of a number of dimetal chemical systems for the systematic interrogation of their ability to reductively couple two NO molecules to produce nitrous oxide (N2O), and (6) detailed investigations of the metal-binding dynamics of nitrogen monoxide in heme, heme/copper and heme/non-heme diiron complexes - such photoinitiated reactions can provide a detailed understanding of the kinetics, thermodynamics, and metal preference/migration of these small molecules in interactions with heme/non-heme metal sites, as is relevant to HCO and NOR biological chemistry.