STRUCTURE AND MECHANISM OF FE-S PROTEINS

我们实验室的目标是确定蛋白质结构在 氧化还原反应，特别是涉及铁的反应：S为电子中心 调职。我们选择了减氮作为一个模式。虽然优雅 光谱研究发现了新的Fe：S和Mo：Fe：S中心 固氮酶蛋白质，我们对该蛋白质的了解有限 结构。然而，无疑是后者影响了 金属中心的性质。对于固氮酶，没有特定的氨基 酸已被认为是电子转移过程的一部分。 目前只确定了铁蛋白的Fe：S中心配体。它 我们打算使用溶液化学方法来研究 蛋白质在催化和电子转移过程中的结构。我们会 将结构变化和化学反应与光谱相关联 铁：S蛋白的性质。在拟议的研究中，铁蛋白 (Av2)和MoFe蛋白(Av1)。 被利用。 今后五年的具体目标是： 1.用光谱方法研究了AV2晶体中Fe：S中心的相互转换 以及化学改性方法。 2.从失活形式中重建具有酶活性的Av2。 3.鉴定ATP/ADP结合位点的氨基酸残基及其相互作用 与铁人的关系：S中锋。 4.确定以Avl为中心的Fe：S和Mo：Fe：S的潜在硫醇配体。 5.确定Av1和Av2上形成复合体的结合区。 6.识别底物中潜在的重要催化残基 减量地点。 7.研究光谱定义明确的简单铁中的硫醇反应性：S 蛋白质。

The goal of our laboratory is to determine the role of protein structure in redox reactions, especially those involving Fe:S centers for electron transfer. We have chosen nitrogen reduction as a model. Although elegant spectroscopic studies have identified new Fe:S and Mo:Fe:S centers in nitrogenase proteins, we have only a limited picture of the protein structure. Yet, it is the latter which undoubtedly influences the properties of the metallo centers. For nitrogenase, no specific amino acids have been identified as part of the electron transfer processes. Only the Fe:S center ligands for the Fe-protein have been determined. It is our intention to use solution chemical methods to study changes in protein structure during catalysis and electron transfer. We will correlate the structural changes and chemical reactivity with the spectral properties of Fe:S proteins. For the proposed studies, the Fe-protein (Av2) and MoFe-protein (Av1) from Azotobacter vinelandii nitrogenase will be used. The specific objectives for the next five years are: 1. To study the interconversion of the Fe:S center in Av2 using spectral and chemical modification methods. 2. To reconstitute enzymatically active Av2 from inactive forms. 3. To identify amino acid residues in the ATP/ADP binding site and their relationship to the Fe:S center. 4. To identify potential thiol ligands of Fe:S and Mo:Fe:S centers in Avl. 5. To identify the binding regions on Av1 and Av2 for complex formation. 6. To identify potential catalytically important residues in the substrate reduction site. 7. To study the thiol reactivity in "simple", spectrally well-defined Fe:S proteins.