Spectroscopic Studies of Blue Copper and Iron Sulfur Electron Transfer Active Sites

斯坦福大学的Solomon教授将对含有金属的活性位点进行研究，这些活性位点相对于同一离子的小分子复合物具有独特的光谱特征。总体目标是了解活性位点的几何和电子结构对生物学中这些位点的反应性的贡献。感兴趣的蛋白质是发生在生物电子转移中的蓝色铜和铁硫中心。这些系统在其自然状态下的独特光谱特征反映了新的电子结构，这些结构影响了还原电位和电子转移动力学。具体来说，这些研究针对的是自然发生或突变蛋白质中的“扰动”蓝铜位点，与经典蓝铜位点相比，它们具有显著的光谱和反应性差异，并且对参与亚硝酸盐还原酶和多铜氧化酶分子内电子转移的蓝铜- cys - his -Type 2（或Type 3）单元上电子耦合的完整轨道路径有了透彻的了解。铁硫的研究将集中在电子对红氧还蛋白铁硫中心氧化还原性能的贡献，并扩展到2-和4-铁硫中心和异质金属簇。这些研究的最终目标是通过实验确定与附加金属中心耦合相关的电子结构的变化，并了解电子离域对还原电位和电子转移反应性的贡献。各种复杂的光谱技术将被用于了解两类含金属蛋白质活性位点的键合。这些蛋白质含有铜硫或铁硫中心，存在于大多数生物体中，并在生理电子传递链中起作用。所采取的方法将需要对活性位点的简单模型进行详细的实验和理论研究，以及对一系列修饰铜蛋白的实验研究。所获得的信息将有助于了解金属位点的键合如何控制这些蛋白质的反应速率和能量学。

Professor Solomon of Stanford University will conduct studies on metal-containing active sites which have unique spectral features relative to small molecule complexes of the same ion. The general goal is to understand these features in terms of the active site geometric and electronic structural contributions to the reactivity of these sites in biology. The proteins of interest are the blue copper and iron-sulfur centers which occur in biological electron transfer. The unique spectral features of these systems in their natural state reflect novel electronic structures which affect the reduction potentials and the kinetics of electron transfer. Specifically, the studies are directed at `perturbed` blue copper sites which occur naturally or in mutated proteins and have significant spectral and reactivity differences relative to classic blue copper sites, and at a thorough understanding of the complete orbital pathway for electron coupling over the blue copper-Cys-His-Type 2 (or Type 3) unit involved in intramolecular electron transfer in nitrite reductase and the multicopper oxidases. The iron-sulfur studies will focus on the contribution of the electronics to the redox properties of the rubredoxin iron-sulfur center, and extension to 2- and 4-iron sulfur centers and to heterometal clusters. The ultimate goal in these studies is to experimentally determine the changes in electronic structure associated with coupling to additional metal centers and to understand the contributions of electron delocalization to the reduction potentials and electron transfer reactivity. A diverse array of sophisticated spectroscopic techniques will be used to learn about the bonding at the active sites of two classes of metal-containing proteins. These proteins contain either copper-sulfur or iron-sulfur centers, are found in most organisms, and function in the physiological electron transport chains. The approach to be taken will entail detailed experimental and theoretical study of simple models of the active sites, as well as experimental study of a series of modified copper proteins. The information obtained will lead to an understanding of how the bonding at the metal sites controls the rates and energetics of reactions of these proteins.