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

血红素/铜和血红素/非血红素铁 O2，无反应性

• 批准号: 6387045
• 负责人: KENNETH D. KARLIN
• 金额: $ 22.48万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-01 至 2004-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6387045
• 关键词: Mossbauer spectrometry; Raman spectrometry; chemical kinetics; chemical reaction; chemical synthesis; copper; cytochrome oxidase; enzyme activity; heme; hemoprotein; iron compounds; iron oxide; iron sulfur protein; metal complex; metalloenzyme; nitric oxide; nuclear magnetic resonance spectroscopy; protonation; stoichiometry; stop flow technique; thermodynamics

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.

长期的研究目标是设计、合成和研究模型化合物系统，以帮助阐明血红素-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（OZ）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。主要的主题是离散血红素/M化合物的合成，还原血红素/Cu组合物的o2化学，血红素/M配合物的配位化学，NO反应性研究，以及在血红素/Cu介导的o2还原中苯酚化学的应用。具体目标包括：(1)使用不同条件的血红素、轴碱或Cu配体对血红素-O2-Cu（过氧）配合物进行光谱和结构表征；(2)研究由单个核组分组装的血红素/Cu/O2加合物；(3)系统比较不同Fe-O2-Cu部分的反应性；(4)发展血红素/M体系的配位化学，以mu-氧、mu-OH-和其他感兴趣的配体（例如C1-、CN-）作为生化探针。(5)还原血红素/M复合物及其CO和异氰化物加合物的研究，(6)对产生氧化亚氮（N2O）的NO还原酶模型系统进行深入研究和阐述，(7)具有不同Fe配体的新血红素/Fe系统，具有三个n供体和/或一个o供体，(8)研究一氧化氮与这些和血红素/Cu系统的反应性，因为NO是一种可逆的CcO抑制剂。(9)利用苯酚作为电子-质子供体和Cu配体在血红素/Cu组装的o2还原中；（10）探索在CcO中发现的咪唑-苯酚（His-Tyr）共价键的形成和功能的相关化学。