Spectroscopic Studies of Copper, Iron Sulfur and Heme Electron Transfer Active Sites

该奖项在无机、生物无机和有机金属化学项目中支持斯坦福大学化学系爱德华·i·所罗门博士对生物兴趣系统中金属介导的电子转移的研究。要研究的系统是蓝铜、铜A、红氧还蛋白、2、3和4铁硫簇和细胞色素。结合光谱方法将用于：1)探索轴向配体在确定蓝铜和铜A中心的电子和几何结构中的作用及其对ET反应性的贡献；2)定义了蓝铜和铜A中心的远距离电子转移共价途径；3)利用变能光电子能谱分析了铁硫团簇的电子结构对Fe(SR)4（1-/2-）中心低还原电位的贡献，以及铁硫团簇在氧化过程中电子结构的变化；4)利用硫k边x射线吸收方法探测导致2、3、4铁团簇和异金属团簇电子离域差异的桥接硫化物键差异，以及蛋白质对团簇电子结构的影响；5)利用金属l边定义细胞色素中氧化还原活性轨道到卟啉配体的共价离域。该研究将利用广泛的光谱方法，包括EPR、极化单晶电子吸收、共振拉曼、圆二色、PES和x射线吸收边缘光谱。电子结构计算将用于解释光谱特征及其相关的电子结构。这些研究将有助于确定电子结构对远距离电子转移的贡献，以及蛋白质在决定活性位点的几何形状和电子结构方面的作用。所研究的蛋白质在生物技术、固氮、呼吸代谢和光合作用中具有重要意义。光谱学方法的发展将在生物学和催化方面有应用。参与本研究的博士后和研究生将接受广泛的光谱方法、配体场和分子轨道计算以及酶学方面的培训，并为在学术界或工业界任职做好准备。仪器将提供给生物无机社区的成员，许多来自美国以外的地方

This award in the Inorganic, Bioinorganic, and Organometallic Chemistry Program supports research by Dr. Edward I. Solomon, Chemistry Department, Stanford University, on metal-mediated electron transfer in systems of biological interest. The systems to be investigated are blue copper, copper A, rubredoxin, the 2, 3, and 4 iron-sulfur clusters, and the cytochromes. A combination of spectroscopic methods will be used to: 1) explore the roles of the axial ligands in determining the electronic and geometric structures of the blue copper and copper A centers and their contributions to ET reactivity; 2) define covalent pathways in blue copper and copper A centers for long range electron transfer; 3) define specific electronic structure contributions to the low reduction potential of the Fe(SR)4(1-/2-) center, and the change in electronic structure of the iron sulfur clusters with oxidation using variable energy photoelectron spectroscopy; 4) probe differences in bridged sulfide bonding that can contribute to differences in electron delocalization in 2, 3, and 4 iron clusters and heterometal clusters and the effects of the protein on the electronic structure of the clusters using sulfur K-edge X-ray absorption methodology; and 5) define the covalent delocalization of the redox active orbital into the porphyrin ligand in the cytochromes using metal L-edges. The studies will utilize a wide range of spectroscopic methods, including EPR, polarized single crystal electronic absorption, resonance Raman, circular dichroism, PES, and X-ray absorption edge spectroscopy. Electronic structure calculations will be used to interpret spectral features and their associated electronic structures.These studies will help determine the contribution of electronic structure to long range electron transfer and the role of the protein in determining the geometry and electronics of the active site. The proteins studied are important in biotechnology, nitrogen fixation, respiratory metabolism, and photosynthesis. Spectroscopic methods developed will have applications in biology and catalysis. Postdoctoral and graduate students involved in this research will be trained in a wide range of spectroscopic methods, ligand field and molecular orbital calculations, and enzymology, and will be well prepared for positions in academia or industry. Instrumentation will be made available to members of the bioinorganic community, many from locations outside the U.S.