CAREER: Unraveling Diverse Mechanisms of Heme Degradation Processes

该奖项的部分资金来自2021年美国救援计划法案（公法117-2）。在化学系生命过程化学项目的支持下，来自圣刘易斯大学的Piotr Mak将研究控制血红素铁依赖酶反应性的基本原理，这些酶在生命系统中起着至关重要的作用，也具有潜在的工业应用。拟议的活动将对理解人类生理学以及无害环境的生物技术过程产生重大的社会影响。预计拟议的强大的研究工具的组合将提供有关血红素蛋白的结构和功能的重要信息，否则不太可能被揭示。拟议工作的另一个重要方面是积极让研究生和本科生参与多学科研究项目，为他们提供广泛的令人兴奋的培训机会。此外，拟议的外展工作将通过制定和实施一项名为“看到无形的东西”的计划，使来自社会经济弱势社区的高中生能够参与科学发现的过程，从而改善在STEM（科学、技术、工程和数学）领域代表性不足的群体的包容性。血红素加氧酶在真核生物和病原体中除了参与血红素催化外，还具有许多重要的生理功能。血红素降解是一个复杂的多步骤过程，尽管经过多年的研究，关于典型血红素加氧酶催化活性中涉及的活性中间体的性质仍然存在重大问题。此外，最近发现的一些非经典酶催化一种新型的血红素降解化学，导致完全不同的代谢产物，这意味着新的和独特的反应途径。虽然它是非常重要的，以阐明这些蛋白质的反应模式，如其活性中间体的性质和结构动力学的因素，进展已被这些不稳定的物种在溶液中进行的反应的极其迅速的衰变所阻碍。本申请提出，共振拉曼光谱与低温辐解和纳米盘取样方法的组合将允许在模拟其自然环境的条件下产生、稳定和表征这些难以捉摸的物质。这种独特的方法有可能提供有关血红素蛋白质的结构-功能关系的信息，这些信息是其他方法无法获得的。这些研究的重要性在于它们对理解氧活化化学的贡献，这是一系列利用双氧的血红素酶和各种其他金属蛋白的基本功能。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in part under the American Rescue Plan Act of 2021 (Public Law 117-2).With the support of the Chemistry of Life Processes Program in the Division of Chemistry, Piotr Mak from Saint Louis University will study fundamental principles that govern the reactivity of heme iron-dependent enzymes, that play crucial roles in living systems and also have potential industrial applications. The proposed activities will have a significant societal impact on understanding human physiology as well as environmentally safe biotechnological processes. It is expected that the proposed combination of powerful research tools will provide vital information regarding the structure and function of heme proteins that is otherwise unlikely to be revealed. Another important aspect of the proposed work is to actively involve graduate and undergraduate students in multi-disciplinary research projects that will provide them with a wide range of exciting training opportunities. Additionally, the proposed outreach efforts will improve inclusion of underrepresented groups in STEM (Science, Technology, Engineering and Mathematics) fields by developing and implementing a program called “Seeing the Invisible”, which will enable high school students from socioeconomically disadvantaged communities to participate in the process of scientific discovery. Heme oxygenases, besides their role in heme catabolism, have many other important physiological functions in eukaryotes and pathogens. Heme degradation is a complex, multi-step process and despite many years of study, significant questions remain regarding the nature of the reactive intermediates involved in the catalytic activity of canonical heme oxygenases. Additionally, some recently discovered noncanonical enzymes catalyze a new type of heme degradation chemistry, leading to entirely different metabolites which imply new and unique reaction pathways. While it is of great importance to elucidate factors that dictate reactivity patterns of these proteins, such as the nature and structural dynamics of their reactive intermediates, progress has been thwarted by the extremely rapid decay of these unstable species for reactions conducted in solution. This application proposes that the combination of resonance Raman spectroscopy with cryo-radiolysis and nanodisc sampling methodology will allow for generation, stabilization, and characterization of these elusive species under conditions that mimic their natural environment. This unique approach has the potential to provide information regarding structure-function relationships in heme proteins that would be inaccessible by alternate methods. The significance of these studies lies in their contribution to the understanding of oxygen activation chemistry, which is an essential function of a wide array of dioxygen-utilizing heme enzymes and various other metalloproteins.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.