Mossbauer Spectroscopy on Nitrogenase Components

9406224 Munck Mossbauer和EPR光谱将用于研究各种铁硫蛋白和模拟这些蛋白活性位点的合成复合物。 拟议的研究的主要重点将是固氮酶，特别强调表征催化反应的中间体。 在这些研究中，蛋白质可以包含一种富含穆斯堡尔同位素57 Fe的簇类型（辅因子中心或P簇），而另一种簇类型包含穆斯堡尔沉默的56 Fe。 这种蛋白质的可用性将大大促进数据分析;此外，它将使我们能够更详细地探测两个簇的电子结构。 还建议研究一氧化碳脱氢酶和两种类型的氢化酶。 其中一种氢化酶含有所谓的H-簇，其化学计量尚未在迄今为止研究的任何系统中确定。 最后，将继续对蛋白质和合成化合物中的3Fe簇进行理论和实验研究。 生物系统每年将超过1000万吨的大气氮转化为氨，氨随后被纳入其他细胞成分。 由于这一过程是农业的基础，许多生物化学家、生物化学家和遗传学家都致力于在分子水平上理解这一过程。 本实验室的研究为阐明固氮酶金属中心的结构作出了重要贡献。 虽然我们过去的研究已经解决了两个新的金属簇在这种酶的结构方面，未来的活动将主要是针对理解的过程中的机制，即定义所涉及的结构后，我们希望阐明固氮过程中发生的顺序事件。 此外，我们希望为无机化学家设计模拟生物过程的催化剂提供结构信息。 我们与固氮酶的斗争涉及到互补的研究，这些研究导致了新的簇的发现，并从根本上对磁性化学产生了新的见解。 该研究计划将涉及固氮酶的生物化学以及各种其他相关蛋白质的研究。 我们对生物化合物的研究将得到适当的化学模型和理论建模研究的补充。 ***

9406224 Munck Mossbauer and EPR spectroscopy will be used to study a variety of iron-sulfur proteins and synthetic complexes that mimic the active sites of these proteins. The major focus of the proposed studies will be nitrogenase, with particular emphasis on characterizing intermediates of the catalytic reaction. For these studies protein is available that contains one cluster type (either the cofactor centers or the P-clusters) enriched with the Mossbauer isotope 57Fe whereas the other cluster type contains the Mossbauer-silent 56Fe. The availability of such protein will facilitate the data analyses substantially; moreover, it will allow us to probe the electronic structure of both clusters in considerably more detail. It is also proposed to study carbonmonoxide dehydrogenase and two types of hydrogenases. One of the hydrogenases contains the so-called H- cluster, the stoichiometry of which has not yet been determined in any system studied thus far. Finally, theoretical and experimental studies of 3Fe clusters that occur in proteins and synthetic compounds will be continued. %%% The biological system converts annually in excess of 10 million tons of atmospheric nitrogen into ammonia, which is subsequently incorporated into other cell constituents. Since this process is fundamental to agriculture, many biochemists, biophysicists and geneticists have directed much effort to understand this process on the molecular level. The research of our laboratory has provided a major contribution to the clarification of the structure of the metal centers of nitrogenase. While our past research has addressed the structural aspects of two novel metal clusters in this enzyme, future activities will be directed mostly towards understanding the mechanism of the process, i.e. after having defined the structure involved we wish to elucidate the sequential events occurring during nitrogen fixation. Moreover, we wish to provide structural information to inorganic chemists for the design of catalysts that mimic the biological process. Our struggles with nitrogenase have involved complementary studies that lead to the discovery of new clusters and to fundamentally new insights into magnetochemistry. The proposal studies will address the biochemistry of nitrogenase as well as research of a variety of other related proteins. Our studies of the biological compounds will be complemented by studies of suitable chemical models and theoretical modelling. ***