Non-heme Fe(IV)-oxo Intermediates: Structure and Reactivity

这个奖项，共同资助的生物分子系统集群在分子和细胞生物科学和无机，化学系的生物无机和有机化学项目支持宾夕法尼亚州立大学的Carsten Krebs和Joseph Bollinger教授研究参与脯氨酰-4-羟化酶（P4 H）活性的Fe（IV）-氧代中间体许多有机分子的生物合成需要选择性氧化反应。特别重要的是脂肪族C-H键的氧化。这个反应特别具有挑战性，因为C-H键的惰性需要极强的氧化剂。此外，大多数有机分子含有多个C-H键，这些C-H键可以被强氧化剂靶向，从而潜在地导致反应混合物。在自然界中，这些反应在金属酶活性位点进行。这些酶能够与分子氧反应以产生高度活性的中间体。这些中间体具有足够的反应性以活化惰性C-H键。含有通过氧代配体配位的+IV氧化态铁的络合物，也称为Fe（IV）-氧代或铁基物质，可以说是已知的最强大、通用和环境友好的氧化剂。详细了解这些中间体的结构和反应性，可以通过动力学和光谱方法的组合获得。动力学方法可以捕获中间体，并提供有关其形成和衰变速度的信息。含有大量活性物质的样品可以通过各种光谱方法进行分析，这些方法可以详细了解它们的化学性质。几种不含血红素辅因子的铁基中间体（a.k.a.非血红素铁基复合物）最近已被Bollinger/Krebs小组详细报道和表征。所研究的酶催化其底物的脂肪族C-H键的羟基化。这项工作现在将扩展到研究其他几种催化不同氧化结果的非血红素铁酶，包括卤化。预计这些研究将提供前所未有的深入了解这些酶用于氧化有机底物的机制。就更广泛的影响而言，这项工作的一个关键特点是它具有高度的跨学科性，符合近年来科学的总体趋势。促进多个相关研究领域的专业知识发展对于有效培训下一代科学家至关重要。本计画系在无机化学、生物化学、分子生物学及物理化学之介面上进行。特别强调酶动力学、配位化学和光谱学的概念。因此，它将促进这些领域的独特培训。共同PI将组织一个夏季研讨会，主题是他们的研究，反应中间体的表征。作为这次研讨会的一部分，将为参加研讨会的学生和研究人员举办一个讲习班。在这次研讨会期间，与会者将接受这一研究领域的实验方法和相关数据解释的培训。期望的是，学生和研究人员将能够更容易地适应这些方法，以自己的研究。

This award, co-funded by the Biomolecular Systems Cluster in the Division of Molecular and Cellular Biosciences and the Inorganic, Bioinorganic and Organometallic Chemistry program in the Division of Chemistry supports research by Professors Carsten Krebs and Joseph Bollinger at the Pennsylvania State University to study Fe(IV)-oxo intermediates involved in the activity of prolyl-4-hydroxylase (P4H).The biosyntheses of many organic molecules require selective oxidation reactions. Of particular importance is the oxidation of aliphatic C-H bonds. This reaction is particularly challenging, because the inertness of the C-H bond requires extremely strong oxidants. Furthermore, most organic molecules contain multiple C-H bonds that could be targeted by the strong oxidant, thus potentially leading to reaction mixtures. In nature, these reactions are carried out at metalloenzyme active sites. The enzymes are capable of reacting with molecular oxygen to create highly reactive intermediates. These intermediates are sufficiently reactive to activate the inert C-H bond. Complexes containing iron in the +IV oxidation state coordinated by an oxo ligand, also known as the Fe(IV)-oxo or ferryl species, are arguably the most powerful, versatile, and environmentally friendly oxidants known. Detailed insight into the structure and reactivity of such intermediates can be obtained by a combination of kinetic and spectroscopic methods. The kinetic methods allow the intermediate to be trapped and provide information about how fast it forms and decays. Samples containing large amounts of the reactive species can then be analyzed by various spectroscopic methods, which provide detailed insight into their chemical nature. Several ferryl intermediates that do not contain the heme cofactor (a.k.a. non-heme ferryl complexes) have recently been reported and characterized in detail by the Bollinger/Krebs group. The enzymes under investigation catalyze the hydroxylation of aliphatic C-H bonds of their substrates. This work will now be extended to study several other non-heme-iron enzymes that catalyze distinct oxidation outcomes, including halogenation. It is expected that these studies will provide unprecedented insight into the mechanisms that these enzymes employ to oxidize organic substrates. In terms of the broader impact, a key feature of this work is that it is highly interdisciplinary, in line with the general trend in science in recent years. Facilitating the development of expertise in multiple, distantly related research areas is imperative for effectively training the next generation of scientists. This project is carried out at the interfaces of inorganic chemistry, biochemistry, molecular biology, and physical chemistry. In particular, it emphasizes concepts of enzyme kinetics, coordination chemistry, and spectroscopy. Thus, it will facilitate unique training in these areas. The co-PIs will organize a summer symposium on the subject of their research, characterization of reaction intermediates. As part of this symposium, there will be a workshop for students and researchers attending the symposium. During this workshop, participants will be trained in the experimental methods of this research area and the associated interpretation of data. The expectation is that students and researchers will be able to adapt these methods more easily to their own research.