Contribution of Ligand Sets to Oxygen Activation in Iron-dependent Biocatalysts

配体组对铁依赖性生物催化剂中氧活化的贡献

• 批准号: 10659063
• 负责人: Yifan Wang
• 金额: $ 37.75万
• 依托单位: UNIVERSITY OF GEORGIA
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2027-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10659063
• 关键词: Active Sites; Address; Aerobic; Alkenes; Binding; Biomimetics; Cell Respiration; Chemistry; Complex; Dioxygen; Engineering; Environment; Enzymes; Funding; Heme; Individual; Investigation; Iron; Isomerism; Kinetics; Knowledge; Life; Ligands; Ligation; Mediating; Metabolic Biotransformation; Molecular; Mycoses; Nature; Nitrogen; Organism; Outcome; Oxidants; Oxygen; Oxygenases; Pathway interactions; Process; Production; Reaction; Research; Scaffolding Protein; Structure; System; Tryptophan; Visual impairment; catalyst; comparative; design; metalloenzyme; porphyrin a; singlet state; visual cycle

Project Summary The central theme of this project is dioxygen activation for C-H/C-C bond functionalization, which is fundamental for aerobic life. Molecular oxygen is a powerful oxidant, but the reaction with ground-state singlet molecules is kinetically unfavorable due to the spin-forbidden nature. To harness the oxidizing power of oxygen and circumvent the unregulated production of reactive oxidative species, metalloenzymes are frequently employed by aerobic organisms to activate oxygen and manipulate biomolecules. Heme and non-heme iron enzymes are two of the most ubiquitous and potent natural catalysts. Representative systems have been well characterized with near-complete mechanistic delineation. However, catalytic pathways of iron-dependent oxygenases with less common ligand sets lack description, and studies emphasizing an individual system do not often consider the intrinsic differences between heme and non-heme coordination. A holistic picture to systematically compare these two systems regarding oxygen activation and reactivity is deficient in the field. This project desires to fill the knowledge gap by investigating how the ligand sets contribute to reaction outcomes and why a particular system exploits one coordination over the other for a specific reaction. An apparent challenge of direct comparison is the massive variability between systems: the selection of ligand donors, active site environment, substrate-binding mode, and overall protein scaffold. To simplify the coordination environment for an unbiased comparison, two unique multifunctional oxygenases are chosen, each with an iron center ligated only by nitrogen-donors. One is a His-ligated heme- dependent enzyme responsible for pyrrolnitrin production, promoting remarkable rearrangement of a tryptophan derivative. The other is a non-heme iron-dependent enzyme crucial for the visual cycle, which catalyzes oxidative alkene cleavage and isomerization using a 4-His ligated ferrous iron. The catalytic mechanisms and structure-function correlations of both enzymes are poorly understood and the ligand sets are rarely found to mediate oxygenation reactions. Over the five-year funding period, we will comparatively investigate the heme and non-heme systems to decode how the atypical ligand sets promote the unusual biotransformations and how oxygen activation is tuned by the presence or absence of a porphyrin ring. Ultimately, the proposed research will leverage the understanding of iron-oxygen chemistry, inspire the design of biomimetic complexes and engineered biocatalysts, and advance the potential for biomedical treatments for fungal infection and impaired vision.

项目摘要 这个项目的中心主题是C-H/C-C键功能化的氧气活化，这是 有氧生活。分子氧是一种强氧化剂，但与基态单重态分子的反应是动力学的。 由于自旋禁止的性质，这是不利的。利用氧气的氧化能力，绕过不受管制的 产生活性氧化物种，金属酶经常被好氧生物用来激活氧气 操控生物分子。血红素和非血红素铁酶是两种最普遍和最有效的天然催化剂。 具有代表性的系统具有近乎完全的机械性描述的特点。然而，催化 铁依赖的加氧酶的途径与较少常见的配体集缺乏描述，研究强调一种 个体系统通常不考虑血红素和非血红素协调之间的内在差异。一个整体性的 对这两个系统的氧活化和反应性进行系统比较的图片在该领域是不足的。这 项目希望通过调查配体集如何对反应结果做出贡献以及为什么 特定的体系利用一种配位比另一种配位进行特定的反应。直接比较显然是一种挑战 是系统之间的巨大差异：配体供体的选择，活性部位环境，底物结合模式， 以及整体的蛋白质支架。为了简化协调环境以实现无偏见的比较，有两个独特的 选择多功能加氧酶，每个加氧酶都有一个只由氮供体连接的铁中心。一个是His连接的亚铁血红素- 一种依赖酶，负责产生吡咯硝胺，促进色氨酸衍生物的显著重排。 另一种是一种对视觉周期至关重要的非血红素铁依赖酶，它催化氧化裂解烯烃和 使用4-组氨酸连接的亚铁进行异构化。二者的催化机理及构效关系 人们对酶知之甚少，也很少发现配位体参与氧合反应。在五年内 资助期内，我们将对血红素和非血红素系统进行比较研究，以破译非典型配体如何设置 促进不寻常的生物转化，以及氧活化如何通过存在或不存在卟啉环来调节。 最终，拟议的研究将利用对铁-氧化学的理解，启发设计 仿生复合体和工程生物催化剂，并促进真菌感染的生物医学治疗的可能性 视力受损。