Heme Oxygenases: chemically complex enzymes found in diverse biological pathways

血红素加氧酶：在多种生物途径中发现的化学复合酶

• 批准号: 10578804
• 负责人: Matthew D Liptak
• 金额: $ 29.98万
• 依托单位: UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-03-01 至 2026-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10578804
• 关键词: Active Sites; Antibiotics; Antioxidants; Biliverdine; Binding; Biochemical Reaction; Biochemistry; Biological; Biological Assay; Carbon; Chemicals; Computer Models; Cytoprotection; Data; Development; Drug Design; Drug Targeting; Enzymes; Eukaryota; Heme; Human; Hydrogen Bonding; Iron; Knowledge; Measures; Modeling; Multienzyme Complexes; Neonatal Jaundice; Optics; Organism; Oxygen; Oxygenases; Pathogenicity; Pathway interactions; Prokaryotic Cells; Proteins; Reaction; Research Project Summaries; Site; Structure; Techniques; analog; biological systems; fascinate; heme a; improved; insight; programs

Project Summary This research program will develop accurate, detailed models of enzymatic heme degradation. In biological systems, heme oxygenases degrade heme to non-heme iron and oxygenated organic products, such as: biliverdin, staphylobilin, and mycobilin. In eukaryotes, the liberated non-heme iron is ultimately recycled into iron-dependent proteins. In prokaryotes, heme oxygenases are often part of iron acquisition pathways whereby pathogenic organisms acquire iron from host-derived heme. Despite a general understanding of the overall reactions catalyzed by heme oxygenases, the mechanistic details of how these enzymes catalyze the insertion of two to three oxygen atoms into a heme substrate remain poorly understood. This mechanistic knowledge is needed to selectively target heme oxygenase without disrupting other heme-dependent proteins. Recently, we developed new optical assays to accurately measure heme binding constants and elucidate the partitioning of heme between heme oxygenases and other heme-dependent proteins. We have also discovered an unprecedented, dynamic out-of-plane distortion of heme within some heme oxygenase active sites, which is correlated with enzymatic activity. Finally, we have revealed that an active site hydrogen bond promotes heme degradation in staphylobilin-producing heme oxygenases by stabilizing a resonance structure with a cationic radical at the carbon site of oxygenation. In the next five years, we will employ a combined spectroscopic and computational approach to elucidate the mechanism of heme monooxygenation to meso-hydroxyheme by mycobilin-producing heme oxygenases, and the mechanisms of meso-hydroxyheme oxygenation by biliverdin- and staphylobilin-producing heme oxygenases. In general, we will employ a variety of spectroscopic techniques to characterize analogues of key enzymatic intermediates. These experimental data will be used to develop accurate computational models of the enzymatic reactions. Ultimately, this program will provide detailed insight into a fascinating chapter of heme biochemistry, namely, self-oxygenation.

项目摘要 该研究计划将开发出酶促血红素降解的准确，详细的模型。在 生物系统，血红素氧酶将血红素降解为非血红素铁和氧化有机产品，例如 AS：biliverdin，葡萄球菌蛋白和霉菌素。在真核生物中，解放的非血红素铁最终被回收为 铁依赖性蛋白。在原核生物中，血红素氧酶通常是铁采集途径的一部分 致病生物从宿主衍生的血红素中获取铁。尽管对整体有一般的了解 由血红素氧酶催化的反应，这些酶如何催化插入的机制细节 在两到三个进入血红素底物的氧原子中，人们对此知之甚少。这种机械知识是 需要选择性地靶向血红素加氧酶，而不会破坏其他血红素依赖性蛋白。最近，我们 开发了新的光学测定，以准确测量血红素结合常数并阐明 血红素氧酶和其他血红素依赖性蛋白之间的血红素。我们还发现了一个 在某些血红素氧酶活性位点，血红素的前所未有的，动态的平面外变形，这是 与酶活性相关。最后，我们揭示了活性位点氢键促进血红素 通过稳定阳离子的谐振结构，在产生葡萄球菌蛋白的血红素氧酶中降解 在氧合的碳部位的根部。在接下来的五年中，我们将采用综合光谱学和 通过计算方法来阐明血红素单二合剂的机理，以介入中羟基蛋白 产生霉菌素的血红素氧化酶，以及双脂蛋白 - 中羟基蛋白氧化的机制 和葡萄球菌蛋白产生的血红素氧酶。通常，我们将采用各种光谱学 表征关键酶中间体的类似物的技术。这些实验数据将用于 开发酶促反应的准确计算模型。最终，该计划将提供 对血红素生物化学的迷人章节的详细见解，即自我氧化。