Elucidating mechanisms of biological hydrogen conversion through model metalloenzymes

在化学学部生命过程化学项目的支持下，俄亥俄州立大学的汉娜·沙法特教授将研究控制含镍酶活性的因素。还原镍酶在多种微生物的代谢过程中至关重要，并执行有价值的反应，如制氢，二氧化碳还原和甲烷氧化。这些高效、复杂的酶以高速率和完全可逆性运作，但尚未在合成系统中精确地复制，留下许多未解之谜。为了更好地了解天然镍酶并学习如何利用这种理解来进行人为过程，Shafaat小组将使用一个强大的蛋白质支架来模拟镍铁氢化酶。对工程酶的研究旨在阐明其反应机理，并确定整个催化蛋白的关键因子。这项研究提供了对天然酶如何在长度和时间尺度范围内发挥作用的见解。研究生、本科生和高中生，包括那些来自服务不足社区的学生，将接受涵盖生物、无机、物理和分析化学的最先进研究技术的培训。该奖项还支持讲座和实践练习的发展，以培训参加国际公认的两年一次的宾夕法尼亚州立大学生物无机研讨会的更广泛的生物无机社区成员。该项目将与大俄亥俄州中部跨多个年龄组的外展计划相结合。该项目旨在通过开发和表征一种模型氢化酶，即镍取代红氧还蛋白（NiRd），解决有关天然存在的镍铁氢化酶和相关镍硫酸盐酶的关键知识空白。由美国国家科学基金会支持的Shafaat小组先前的工作已经确定，nrd是氢化酶的功能模拟物，表现出高的氢演化率。在提出的工作中，包括电子顺磁共振、核磁共振、共振拉曼和x射线吸收在内的光谱技术将与电化学方法相结合，以获得高分辨率的机制信息，并揭示氢析氢活性的分子水平贡献者。这些研究将为蛋白质支架在模型和天然金属酶中施加的控制层提供详细的见解。这项工作的目标是确定酶的结构和功能之间的相关性，并推进我们对生物氢转化的理解。该研究还寻求确定高活性人工金属酶的设计原则，对小分子活化反应可持续催化剂的发展具有长期意义。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。

With the support of the Chemistry of Life Processes Program in the Chemistry Division, Professor Hannah Shafaat of The Ohio State University will investigate the factors that govern the activity of nickel-containing enzymes. Reductive nickel enzymes are critical in the metabolic processes of diverse microorganisms and perform valuable reactions such as hydrogen production, carbon dioxide reduction, and methane oxidation. These efficient, complex enzymes operate with high rates and full reversibility but have yet to be accurately reproduced in synthetic systems, leaving many questions unanswered. To better understand native nickel enzymes and learn how to harness this understanding for anthropogenic processes, the Shafaat group will model the nickel-iron hydrogenases using a robust, protein-based scaffold. The proposed studies on the engineered enzymes are aimed at the elucidation of the reaction mechanisms along with the identification of the key factors along the entire protein contributing to catalysis. The research provides insight into how natural enzymes function across a range of length- and timescales. Graduate, undergraduate, and high-school students, including those from underserved communities, will be trained in state-of-the-art research techniques spanning biological, inorganic, physical, and analytical chemistry. This award also supports the development of lectures and hands-on exercises to train members of the broader bioinorganic community who attend the internationally recognized, biennial Penn State Bioinorganic Workshop. This project will be integrated with outreach programs spanning multiple age groups in greater Central Ohio. This project seeks to address critical knowledge gaps about the naturally occurring nickel-iron hydrogenases and related nickel-thiolate enzymes through the development and characterization of a model hydrogenase enzyme, namely nickel-substituted rubredoxin (NiRd). Prior work supported by the NSF in the Shafaat group has established that NiRd is a functional mimic of hydrogenase that exhibits high rates for hydrogen evolution. In the proposed work, spectroscopic techniques, including electron paramagnetic resonance, nuclear magnetic resonance, resonance Raman, and X-ray absorption, coupled with electrochemical methods, will be employed to obtain high-resolution mechanistic information and to reveal molecular-level contributors to hydrogen evolution activity. These studies will provide detailed insight into the layers of control exerted by the protein scaffold in both model and native metalloenzymes. The goals of the work are to identify correlations between enzymatic structure and function and to advance our understanding of biological hydrogen conversion. The research seeks also to identify design principles for highly active artificial metalloenzymes, with long-term implications for the development of sustainable catalysts for small molecule activation reactions.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.