HEME/COPPER AND HEME/NONHEME IRON O2 AND NO REACTIVITY

长期的研究目标是设计、合成和研究模型化合物体系，以帮助阐明与血红素-铜氧化酶(如细胞色素c氧化酶)和一氧化氮还原酶所利用的化学有关的结构、金属连接、光谱和反应的基本方面。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(OZ)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-激活、NO和氮氧化物化学和生物化学以及环境中与氮氧化物相关的问题提供基础见解。主要主题是离散的血红素/M化合物的合成，还原的血红素/铜组装的O2化学，血红素/M络合物的配位化学，NO反应活性研究，以及苯酚化学在血红素/铜介导的O2-还原中的应用。具体目标包括(1)利用不同的血红素、轴碱或铜配体的条件来表征血红素-O2-铜(过氧基)络合物的光谱和结构，(2)研究由单核组分组装的血红素/铜/O2加合物，(3)系统地比较不同Fe-O2-铜部分的反应活性，(4)发展以Mu-oxo、Mu-OH-和其他感兴趣的配体(例如，C1-、CN-)作为生化探针的血红素/M体系的配位化学，(5)还原的血红素/M络合物及其CO和异氰化物加合物的研究，(6)深入研究和阐述产生一氧化二氮(N2O)的NO还原酶模型系统，(7)生成具有三个N-供体和/或一个O-供体的不同铁配体的新的血红素/铁体系，(8)研究一氧化氮与这些和血红素/铜体系的反应活性，因为NO是CcO的可逆抑制物，(9)使用酚作为电子质子供体和铜配体与血红素/铜组件进行O2还原，以及(10)探索与在CcO中发现的咪唑-苯酚(His-Tyr)共价键的形成和功能相关的化学。

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. 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 (OZ) 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 of discrete heme/M compounds, O2-chemistry of reduced heme/Cu assemblies, the coordination chemistry of heme/M complexes, NO reactivity studies, and use of phenol chemistry in heme/Cu mediated O2-reduction. Specific aims include (1) spectroscopic and structural characterization of heme-O2-Cu (peroxo) complexes using varied conditions of heme, axial base, or Cu-ligand, (2) study of heme/Cu/O2 adducts assembled from mononuclear components, (3) systematic comparisons of the reactivity of varying Fe-O2-Cu moieties, (4) development of the coordination chemistry of heme/M systems with mu-oxo, mu-OH- and other ligands (e.g., C1-, CN-) of interest as biochemical probes, (5) study of reduced heme/M complexes and their CO and isocyanide adducts, (6) thorough investigation and elaboration upon a NO reductase model system which produces nitrous oxide (N2O), (7) generation of new heme/Fe systems having varied Fe-ligands with three N-donors and/or with one O-donor, (8) study of nitric oxide reactivity with these and heme/Cu systems, since NO is a reversible inhibitor of CcO, (9) use of phenols as electron-proton donors and Cu-ligands in O2-reduction with heme/Cu assemblies, and (10) probing of the chemistry relevant to formation and function of an imidazole-phenol (His-Tyr) covalent link found in CcO.