EAGER: Bio-Inorganic Chemistry of the Rare Earth Metals: Chemistry Relevant to the Cerium-Dependent Methanol Dehydrogenase

这项通过化学系生命过程化学计划和化学催化计划获得的早期概念探索研究(AGER)奖将资助宾夕法尼亚大学的Eric Schelter博士研究第一个含稀土金属酶活性中心的功能模型络合物的电子结构，并合成用于醇类脱氢的新的高效催化剂。最近发现，在意大利索法塔拉陨石坑发现的一种有机体烟曲霉菌SoIV需要稀土金属才能生长。这一令人惊讶的发现标志着首次发现了生命所必需的稀土元素。最近还确定，生物体在一种关键酶中含有一个Ce原子，该酶用于将甲烷转化为生物体的食物来源。这个项目的重点是确定Ce中心到底是如何做到这一点的，以及稀土元素在维持这些微生物存活方面所起的作用。这项工作将对我们理解生命的基本特征以及生命需要什么才能维持产生广泛的影响，即使在极端恶劣的环境中也是如此。通过这个项目培养的研究生将在生物无机化学和化学催化的界面上获得独特和多样化的技能。该项目的结果将通过针对高中生和普通公众的外展项目进行传达。代表不足的群体，包括女研究生、一名非裔美国研究生、一名来访的非洲女科学家和一名拉丁裔博士后助理，将从该项目的支持中受益。最近的研究表明，甲基营养烟曲霉菌对稀土金属La-Gd有必要的生长需求。Fumariolicum Solv的甲醇脱氢酶的活性部位含有一个Ce阳离子。这一令人惊讶的发现标志着稀土元素(RE=La-Gd，Sc和Lu)第一次被证明具有重要的生物化学作用。这一应用的中心假设是，Ce的金属氧化还原活性可以用来评估活性中心的电子结构，Ce-Quone配合物在模型化合物中也会类似地诱导甲醇脱氢，而稀土离子的强Lewis酸性使Ce-甲醇脱氢酶具有快速而独特的反应活性。该团队将通过模型络合物合成、电化学和密度泛函理论研究的组合来检验这一假说。研究的总体目标是确定Ce活性中心的电子结构，并合成催化醇脱氢的酶的功能模型络合物。

This EArly-concept Grant for Exploratory Research (EAGER) award through the Chemistry of Life Processes Program and Chemical Catalysis Program in the Division of Chemistry is funding Dr. Eric Schelter of the University of Pennsylvania to study the electronic structure of functional model complexes of the active site of the first rare earth-containing metalloenzyme and to synthesize new efficient catalysts for the dehydrogenation of alcohols. It has been recently discovered that M. fumariolicum SoIV, an organism found in the Sofatara Crater in Italy, requires rare earth metals in order to grow. This surprising finding marks the first time that any rare earth elements have been found to be necessary for life. It has also been recently determined that the organism possesses a cerium atom in a key enzyme used to convert methane into a food source for the organism. This project is focused on determining exactly how the cerium center does this and what the role of the rare earth elements are in keeping these microbes alive. This work will have a broad impact on our understanding of the basic features of life and what is required for life to be sustained, even in extremely harsh environments. Graduate students trained through this project will acquire unique and diverse skills at the interface of bioinorganic chemistry and chemical catalysis. The findings of the project will be communicated through outreach programs targeted toward high school students and the general public. Underrepresented groups including women graduate students, an African American graduate student, a visiting African woman scientist and a Latino postdoctoral associate will benefit from support of the project. Recent studies have shown that the methylotrophic M. fumariolicum SolV has an essential growth requirement for the rare earth metals La-Gd. The methanol dehydrogenase enzyme of M. fumariolicum SolV was determined to have a cerium cation in its active site. This surprising finding marked the first instance that rare earth elements (RE = La-Gd, Sc and Lu) were shown to have an essential biochemical role. The central hypothesis of this application is that the metal redox activity of Ce can be used to evaluate the electronic structure of the active site, that Ce-quinone complexes will similarly induce methanol dehydrogenation in model complexes, and that the strong Lewis acidity of RE cations enable fast and unique reactivity for the cerium methanol dehydrogenase. The team will test the hypothesis through a combination of model complex synthesis, electrochemistry and density functional theory studies. The overall goals of the research are to determine the electronic structure of the cerium active site and to synthesize functional model complexes of the enzyme that catalyze the dehydrogenation of alcohols.