Spectroscopic Characterization of Oxygen Intermediates in Non-heme and Heme Iron Enzymes

非血红素和血红素铁酶中氧中间体的光谱表征

• 批准号: 10396809
• 负责人: EDWARD I SOLOMON
• 金额: $ 45.17万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-05-01 至 2027-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10396809
• 关键词: Active Sites; Anabolism; Antibiotics; Biology; Bioremediations; Biotechnology; Chemistry; Coenzymes; Collagen; Crystallization; Disease; Engineering; Environment; Enzymes; Health; Heme; Heme Iron; Human; Hydrogen Peroxide; Hydroxylation; Hypoxia; Iron; Methane; Methane hydroxylase; Methods; Molecular; Mononuclear; Natural Products; Nature; Oxygen; Oxyhemoglobin; Play; Pterins; Reaction; Regulation; Research; Role; Structure; Thermodynamics; alpha ketoglutarate; base; catalyst; chromophore; drug metabolism; electronic structure; geometric structure; halogenation; insight; metalloenzyme; novel therapeutics; rational design

Project summary Iron enzymes play major roles in O2 activation in biology. These divide into four classes based on their active site structures that reflect their mode of O2 activation: the non-cofactor dependent mononuclear non-heme iron (MNHFe) enzymes, the cofactor (α-ketoglutarate (α-KG) and pterin) dependent MNHFe enzymes, the binuclear NHFe enzymes and the O2/H2O2 activating heme enzymes. Crystal structures and oxygen reaction intermediates exist for metalloenzymes in all four classes. Over the years, we have developed new spectroscopic methods enabling the detailed study of the NHFeII active sites, and the geometric and electronic structures of their O2 intermediates and have now developed a method to quantitatively study the iron center in the highly covalent and chromophoric heme environment. Among our accomplishments in the past 5 years are: 1) determined that FeIII-O2- species are the reactive intermediates in all the subclasses of non-cofactor dependent MNHFe enzymes; 2) defined the O2 reaction coordinates to generate the FeIV=O intermediates in both the α-KG and pterin dependent enzymes; 3) for the α-KG dependent subclass, defined the geometric and electronic structures of their FeIV=O enzyme intermediates and how these direct halogenation over the thermodynamically favored hydroxylation in the halogenases; 4) showed that in contrast to the MNHFe enzymes, hydroperoxide intermediates are active in the binuclear NHFe enzymes for direct reaction with substrates; 5) for methane monooxygenase, where the peroxo-biferric intermediate rapidly converts to a high-valent 2FeIV-oxo intermediate Q, we have determined the structure of Q (a topic of current debate) and provided insight into its high reactivity with methane; 6) used the spectroscopic method we have now developed for iron in heme environments to determine experimentally the computationally controversial electronic structure of oxyhemoglobin; 7) and extended this method to analyze active sites with strong Fe-oxo bonds. Our studies are now directed toward completing the reaction coordinates of the four classes and their subclasses, understanding O2 activation at the superoxo, peroxo and FeIV-oxo levels, determining the role of the second iron in the enhanced reactivity of the binuclear NHFe enzymes, and understanding the differences in the activation and selectivity of high-valent iron-oxo intermediates in mononuclear NH, binuclear NH and heme enzyme active sites.

项目概要 铁酶在生物学中的 O2 活化中发挥着重要作用，它们根据不同的性质分为四类。 它们的活性位点结构反映了 O2 激活模式：非辅因子依赖性 单核非血红素铁 (MNHFe) 酶、辅因子（α-酮戊二酸 (α-KG) 和蝶呤） 依赖性 MNHFe 酶、双核 NHFe 酶和 O2/H2O2 激活血红素 所有金属酶都存在晶体结构和氧反应中间体。 多年来，我们开发了新的光谱方法。 NHFeII 活性位点及其 O2 的几何和电子结构的详细研究 中间体，现已开发出一种定量研究铁中心的方法 高度共价和发色血红素环境是我们过去 5 年来取得的成就之一。 年是：1) 确定 FeIII-O2- 物质是所有子类中的反应性中间体 非辅因子依赖的 MNHFe 酶；2) 定义 O2 反应坐标以生成 α-KG 和蝶呤依赖性酶中的 FeIV=O 中间体；3) 对于 α-KG 依赖子类，定义了 FeIV=O 酶的几何和电子结构 中间体以及这些直接卤化如何优于热力学 卤化酶中的羟基化；4)表明与MNHFe酶相比， 氢过氧化物中间体在双核 NHFe 酶中具有活性，可直接与 5) 对于甲烷单加氧酶，其中过氧化二铁中间体快速 转化为高价2FeIV-oxo中间体Q，我们确定了Q的结构（a 当前辩论的主题）并深入了解其与甲烷的高反应性；6）使用 我们现在开发了血红素环境中铁的光谱方法来确定 实验上计算出有争议的氧合血红蛋白电子结构 7) 和 我们现在正在研究如何扩展这种方法来分析具有强铁氧键的活性位点。 旨在完成四个类及其子类的反应坐标， 了解 O2 在超氧、过氧和 FeIV-氧水平上的活化，确定 第二种铁增强双核 NHFe 酶的反应性，并了解 高价铁氧中间体的活化和选择性的差异 单核 NH、双核 NH 和血红素活性酶位点。