O2-Reactivity in De Novo Designed Mononuclear, Non-Heme Fe Proteins

项目摘要/摘要： 金属酶进行化学转化，其速度和选择性保持在 令合成化学家羡慕不已。根据定义，这些转变利用了地球丰富的过渡 金属和环保试剂。此外，虽然一些金属酶利用 专门的辅因子，许多都能够实现这些转换使用相对有限的 天然配体集所提供的氨基酸。事实上，在许多情况下，一个单一的协调主题 用于促进各种机械上截然不同的转换，为 蛋白质环境的二级和三级结构对决定反应的重要性 机制。理解结构-功能原理的一种方法是从头设计 金属酶从无到有。在这里，我们利用从头开始的蛋白质设计，使我们能够 有系统地改变具有生物重要性的双亲反应周围的当地环境 中间体，铁的超氧化合物。然后，我们寻求利用这种理解和新发现的 有能力设计特定的小分子结合蛋白来探索生理上重要的C- H在单核、非血红素铁中心的活化反应。C-H活化反应是 从结构-功能的角度特别感兴趣，因为它们的成功已经显示出来 高度依赖于衬底定位，从而提供了对我们能力的敏感测试 全新设计的捆绑口袋。提高我们设计受控捆绑袋的能力将 为从头蛋白的许多应用打开了可能性。拟议的研究将主要 使用光学光谱学来表征电子结构和 不同物种的热化学。这些研究将得到结构性研究的补充 来自多核核磁共振波谱和X射线结晶学的信息。结果是 将代表着蛋白质设计的突破，并对基本理解产生影响 金属蛋白如何利用简单的配位体生成和利用活性中间体 以实现化学上具有挑战性的转变。

Project Summary/Abstract: Metalloenzymes perform chemical transformations with rates and selectivities that remain the envy of synthetic chemists. By definition these transformations utilize earth-abundant transition metals and environmentally friendly reagents. Furthermore, while some metalloenzymes utilize specialized cofactors, many are able to achieve these transformations using the relatively limited natural ligand set provided by the amino acids. Indeed, in many cases a single coordination motif is used to promote a variety of mechanistically distinct transformations providing evidence for the important of the secondary and tertiary structure of the protein environment for dictating reaction mechanism. One approach to understanding the structure-function principles is to de novo design metalloenzymes from scratch. Herein we exploit de novo protein design to allow us to systematically alter the local environment around a biologically important, ambiphilic reaction intermediate, the ferric superoxo. We then seek to utilize this understanding and the newfound ability to design specific small molecule binding proteins to explore physiologically important C– H activation reactions at a mononuclear, non-heme Fe center. C–H activation reactions are of particular interest from a structure-function perspective because their success has been shown to be highly dependent on substrate positioning, thereby providing a sensitive test of our ability to de novo design binding pockets. Improving our ability to design controlled binding pockets would open the possibility for many applications of de novo proteins. The proposed studies will primarily be achieved using optical spectroscopy to characterize the electronic structure and thermochemistry of the different species. These studies will be complemented by structural information derived from multinuclear NMR spectroscopy and X-ray crystallography. The results would represent a breakthrough in protein design with implications for fundamental understanding of how metalloproteins utilize simple ligand sets to generate and harness reactive intermediates for achieving chemically challenging transformations.