CAREER: Unraveling Diverse Mechanisms of Heme Degradation Processes

该奖项部分由2021年美国救援计划法案（公法117-2）资助。在圣路易斯大学化学系生命过程化学项目的支持下，来自圣路易斯大学的Piotr Mak将研究控制血红素铁依赖性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，也有潜在的工业应用。拟议的活动将对了解人类生理学以及对环境安全的生物技术过程产生重大的社会影响。预计这些强大的研究工具将提供有关血红素蛋白结构和功能的重要信息，否则这些信息不太可能被揭示。建议工作的另一个重要方面是积极地让研究生和本科生参与多学科研究项目，这将为他们提供广泛的令人兴奋的培训机会。此外，拟议的推广工作将通过制定和实施一项名为“看到看不见的”的计划，改善STEM（科学、技术、工程和数学）领域中代表性不足的群体的包容性，该计划将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。血红素加氧酶除了在血红素分解代谢中起作用外，在真核生物和病原体中还具有许多其他重要的生理功能。血红素降解是一个复杂的、多步骤的过程，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，最近发现的一些非典型酶催化一种新的血红素降解化学，导致完全不同的代谢物，这意味着新的和独特的反应途径。虽然阐明决定这些蛋白质的反应模式的因素非常重要，例如它们的反应中间体的性质和结构动力学，但这些不稳定的物质在溶液中进行反应时的极快衰变阻碍了进展。该应用表明，共振拉曼光谱与低温辐射分解和纳米圆盘采样方法的结合将允许在模拟自然环境的条件下产生，稳定和表征这些难以捉摸的物种。这种独特的方法有可能提供关于血红素蛋白结构-功能关系的信息，这是其他方法无法获得的。这些研究的意义在于它们对氧活化化学的理解的贡献，氧活化化学是广泛的利用双氧的血红素酶和各种其他金属蛋白的基本功能。该奖项反映了美国国家科学基金会的法定使命，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.