Structure and Dynamics of CO Binding to Nitrogenase via Ultrafast Vibrational Spectroscopy

固氮酶是催化氮转化为氨的重要酶，在全球氮循环中起着关键作用。最近，它们还被证明可以将一氧化碳(CO)转化为碳氢化合物，因此被认为是生产生物燃料的重要候选者。凭借这一奖项，美国国家科学基金会化学部生命过程化学计划资助加州大学欧文分校的葛念辉教授研究一氧化碳如何与固氮酶结合并相互作用。虽然固氮酶已经得到了很好的研究，但对CO结合和反应的详细机制仍然缺乏。这个项目将应用最先进的超快振动光谱学来捕获分子运动，使用比万亿分之一秒快的“快门速度”的激光脉冲。这些快照提供了关于一氧化碳和固氮酶相互结合和相互作用时的分子结构和瞬时动力学的新的和迫切需要的信息。参与研究的研究生利用先进的激光技术和核心物理科学进行宝贵的培训，以加强他们的职业发展。该项目还与通过科学示范吸引K-12学生参与的外联工作相结合。这个项目是通过超快二维红外光谱的新应用和各种瞬变测量来获得CO与依赖钼和钒的固氮酶结合的分子图像。这些技术的高时间分辨率使得研究酶的快速结构波动和转变成为可能。结合计算模型，这些实验揭示了CO在结合部位的结构，阐明了辅因子周围的局部环境，并建立了不同CO物种之间的连接性。从这个项目获得的详细的结构和动态信息提供了新的见解，并有助于建立一氧化碳与氮素结合的统一机制。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Nitrogenases are important enzymes that catalyze the conversion of nitrogen to ammonia and play key roles in the global nitrogen cycle. Recently, they have also been shown to convert carbon monoxide (CO) to hydrocarbons and, therefore, are recognized as important candidates for the production of biofuels. With this award, the Chemistry of Life Processes Program in the Division of Chemistry at NSF is funding Professor Nien-Hui Ge from the University of California, Irvine, to investigate how CO binds to and interacts with nitrogenases. Although nitrogenases have been well studied, the detailed mechanisms for CO binding and reactions are still lacking. This project will apply state-of-the-art ultrafast vibrational spectroscopy to capture molecular motions using laser pulses at "shutter speeds" faster than one-trillionth of a second. These snap-shots provide new and much needed information on the molecular structure and transient dynamics of CO and nitrogenases as they bind and interact with each other. Graduate students participating in the research gain valuable training with advanced laser techniques and core physical sciences to strengthen their career development. This project is also integrated with outreach efforts that engage K-12 students through scientific demonstrations. This project is undertaken to gain a molecular picture of CO binding to molybdenum- and vanadium-dependent nitrogenases by novel applications of ultrafast two-dimensional infrared spectroscopy and a variety of transient measurements. The high time resolution of these techniques allows the study of rapid structural fluctuations and transitions of the enzyme. When combined with computational modeling, these experiments reveal the structure of CO at binding sites, elucidate local environment around the cofactor, and establish connectivities between different CO species. Detailed structural and dynamic information obtained from this project provides new insight and helps to establish a unified mechanism for CO binding to nitrogenases.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.