Time Resoved Vibration Spectrocopy of Functioning Substrate-Bound Nitrogenase

这个无机、生物无机和有机金属化学项目的奖项支持加州大学河滨分校的Stephen P. Cramer教授通过使用时间分辨红外（TR-IR）光谱和相关技术来阐明氮酶的原子水平机制。氮酶生物化学和TR-IR光谱的最新进展为确定大气中氮气生物还原为土壤中可供植物生长的氨的化学基础提供了前景。具体目的是使用：1)TR-IR光谱来确定在周转条件下MoFe氮酶的底物结合形式。2)红外动力学研究MoFe氮酶的作用机制，特别是在翻转过程中关键氨基酸残基和高柠檬酸盐的变化。3)利用太赫兹（Far-IR）光谱研究与MoFe:Fe蛋白复合物形成相关的构象模式。功能氮酶的红外动力学将用于探索机制方面，如质子易位，伴随能量消耗ATP水解的蛋白质构象变化，以及酶转换过程中氮酶蛋白质复合物的形成和解离。本研究的广泛影响包括：1)利用加州大学戴维斯分校、犹他州立大学、中佛罗里达大学和劳伦斯伯克利国家实验室的先进设备，以及ALS、伯克利和杰斐逊实验室的同步辐射仪器，促进教学、培训和学习。2)通过暑期实习，建立一个项目，让未被充分代表的群体（少数民族和残疾人）参与到高中水平。3)通过建立独特的科学仪器（TR-IR低容量仪器）和广泛的合作，建立研究和教育基础设施。

This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports Professor Stephen P. Cramer at the University of California at Riverside to elucidate the atomic-level mechanism of the nitrogenase enzyme by using time-resolved infra-red (TR-IR) spectroscopy with related techniques. Recent advances in nitrogenase biochemistry and TR-IR spectroscopy offer the prospect of determining the chemistry underpinning biological reduction of nitrogen gas in the atmosphere to ammonia available in soils for plant growth. Specific aims are to use: 1) TR-IR spectroscopy to speciate substrate bound forms of MoFe nitrogenase under turnover conditions. 2) IR kinetics to probe the mechanism of MoFe nitrogenase, particularly with regard to changes in key amino-acid residues and homocitrate during turnover. 3) Terahertz (Far-IR) spectroscopy to study the conformation modes associated with MoFe:Fe protein complex formation. IR kinetics of functioning nitrogenase will be used to probe mechanistic aspects such as proton translocation, changes in the protein conformational concomitant with the energy consuming ATP hydrolysis, and formation and dissociation of the nitrogenase protein complex during enzyme turnover. The broader impacts of this research include: 1) Promoting teaching, training and learning by using state of the art facilities at the University of California Davis, Utah State University, the University of Central Florida and Lawrence Berkeley National Laboratory as well as synchrotron radiation instrumentation at the ALS, Berkeley and Jefferson Laboratory. 2) Establishing a program to involve underrepresented groups (ethnic and disabled) at the high school level through summer internships. 3) The establishment of infrastructure for research and education through both the establishment of unique scientific instrumentation (the TR-IR low volume apparatus) and wide ranging collaborations.