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.

项目概要 该项目的中心主题是 C-H/C-C 键功能化的双氧活化，这是 有氧生活。分子氧是一种强氧化剂，但与基态单线态分子的反应在动力学上是 由于自旋禁止的性质而不利。利用氧气的氧化能力并规避不受管制的 产生活性氧化物质，需氧生物经常使用金属酶来激活氧气 并操纵生物分子。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。 代表性系统已经得到了很好的表征，具有近乎完整的机械描述。然而，催化 具有不太常见配体组的铁依赖性加氧酶的途径缺乏描述，并且研究强调 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。一个整体的 该领域缺乏系统地比较这两个系统关于氧活化和反应性的图片。这 该项目希望通过研究配体组如何影响反应结果以及为什么会出现这种情况来填补知识空白。 特定的系统利用一种协调而不是另一种协调来实现特定的反应。直接比较的明显挑战 是系统之间巨大的可变性：配体供体的选择、活性位点环境、底物结合模式， 和整体蛋白质支架。为了简化协调环境以进行公正的比较，两个独特的 选择多功能加氧酶，每个加氧酶都具有仅由氮供体连接的铁中心。一种是His-连接的血红素- 负责吡咯尼群产生的依赖性酶，促进色氨酸衍生物的显着重排。 另一种是对视觉循环至关重要的非血红素铁依赖性酶，它催化氧化烯烃裂解和 使用 4-His 连接亚铁进行异构化。两者的催化机制和结构功能相关性 人们对酶知之甚少，并且很少发现配体组可以介导氧化反应。五年来 资助期间，我们将比较研究血红素和非血红素系统，以解码非典型配体如何设置 促进不寻常的生物转化以及如何通过卟啉环的存在或不存在来调节氧的活化。 最终，拟议的研究将利用对铁氧化学的理解，启发设计 仿生复合物和工程生物催化剂，并提高真菌感染生物医学治疗的潜力 和视力受损。