Heme/Copper and Heme/Non-Heme Iron O2 and NO Reactivity

描述(申请人提供)：长期研究目标是设计、合成和研究模型化合物系统，该系统可以帮助阐明结构、金属连接、光谱和与血红素-铜氧化酶(例如，细胞色素c氧化酶(CCOs))和一氧化氮还原酶(NORs)所利用的化学有关的基本方面。这些进化上相关的酶参与了好氧和厌氧生物的生物能量学，并具有共同的血红素/M(M=铜或非血红素铁)活性部位，分别还原分解氧气(O2)或一氧化氮(NO)。这项研究有助于更好地理解酶的结构和机制，并为生物O2的激活、NO和氮氧化物的化学和生物化学以及环境中氮氧化物的相关问题提供基本的见解。主要内容包括离散的血红素/M化合物的合成和表征，它们与O2和NO的反应活性研究，血红素/M络合物的配位化学和光化学，以及血红素/铜/O2加合物的还原O-O键断裂。具体目标包括(1)进一步表征和阐明现有的血红素-过氧铜配合物的过氧连接性和电子结构，(2)利用包括交联咪唑-苯酚部分的体系的各种三齿铜配体对血红素/铜/氧的化学进行扩展研究，(3)低自旋血红素-过氧铜配合物的合成和表征，(4)研究和阐述产生一氧化二氮(N2O)的NOR模型体系的化学，(5)一氧化氮与血红素/铜配合物的反应活性研究，(6)血红素-O(H)-M体系配位化学的发展；(7)光化学诱导的血红素/金属络合物中原子/配体/电子转移的研究；(8&9)通过控制H+、e-和/或H源或采用低温还原、伽马辐照技术研究血红素/铜/O_2加合物的还原O-O键断裂。

DESCRIPTION (provided by applicant): 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 (e.g., cytochrome c oxidases (CcOs)) and nitric oxide reductases (NORs). These evolutionarily related enzymes are involved in the bioenergetics of aerobic and anaerobic organisms, and have in common a heme/M (M = Cu or non-heme Fe) active site, which reductively cleaves dioxygen (O2) or nitric oxide (NO), respectively. The research can contribute to a better understanding of enzyme structure and mechanism, and provide fundamental insights into biological O2 activation, NO and nitrogen oxide chemistry and biochemistry, and issues related to nitrogen oxides in the environment. Major themes are the synthesis and characterization of discrete heme/M compounds, their reactivity studies with O2 and NO, the coordination chemistry and the photochemistry of heme/M complexes, and the reductive O-O bond cleavage of heme/Cu/O2 adducts. Specific aims include (1) further characterization and elucidation of the peroxo-connectivity and electronic structures of existing heme-peroxo- Cu complexes, (2) expanded studies on heme/Cu/O2 chemistry employing various tridentate Cu-ligands which include systems with a cross-linked imidazole-phenol moiety, (3) synthesis and characterization of low-spin heme-peroxo-Cu complexes, (4) investigation and elaboration of the chemistry of NOR model systems which produce nitrous oxide (N2O), (5) study of nitric oxide reactivity with heme/Cu complexes, (6) development of the coordination chemistry of heme-O(H)-M systems, (7) investigation of atom/ligand/electron transfer in heme/M complexes induced by photochemistry, and (8 & 9) study of reductive O-O bond cleavage of heme/Cu/O2 adducts either by controlling H+, e-, and/or H. sources, or by employing a cryoreduction, gamma-irradiation technique.