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

描述（由申请人提供）：长期研究目标是设计、合成和研究模型化合物体系，这有助于阐明血红素-铜氧化酶（如细胞色素c氧化酶（CcOs））和一氧化氮还原酶（NORs）所利用的化学相关的结构、金属连接、光谱和反应性的基本方面。这些进化相关的酶参与好氧和厌氧生物的生物能量学，并具有共同的血红素/M （M = Cu或非血红素Fe）活性位点，分别还原裂解二氧（O2）或一氧化氮（NO）。该研究有助于更好地了解酶的结构和机制，为生物O2活化、NO和氮氧化物化学和生物化学以及环境中氮氧化物的相关问题提供基础见解。主要的研究主题是离散血红素/M化合物的合成和表征，它们与O2和NO的反应性研究，血红素/M配合物的配位化学和光化学，以及血红素/Cu/O2加合物的还原O-O键裂解。具体目标包括：(1)进一步表征和阐明现有血红素-过氧-Cu配合物的过氧连通性和电子结构；(2)利用各种三牙铜配体（包括交联咪唑-苯酚部分的系统）扩展血红素/Cu/O2化学研究；(3)低自旋血红素-过氧-Cu配合物的合成和表征；(4)研究和阐述产生氧化亚氮（N2O）的NOR模型系统的化学性质。(5)研究一氧化氮与血红素/Cu络合物的反应性；(6)发展血红素- o (H)-M体系的配位化学；(7)研究光化学诱导血红素/M络合物中的原子/配体/电子转移；（8和9）研究血红素/Cu/O2加合物的还原性O-O键裂解，通过控制H+、e-和/或H源，或采用低温还原、γ辐照技术。

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.