Spectroscopic Elucidation of Electronic Structure Contributions to Electron Transfer and Oxo-Atom Transfer

本奖项由化学系化学结构，动力学和机制（CSDM）计划爱德华一。斯坦福大学的所罗门支持使用广泛的光谱方法结合电子结构计算，以了解参与生物电子转移（ET）和含氧原子转移（OAT）的金属蛋白活性位点的独特光谱特征。新颖的活性位点几何和电子结构可以对反应性做出重大贡献。作为该计划的一部分，开发了新的光谱方法，包括：变温变场磁圆二色性（VTVH MCD）来分配电子跃迁并使用激发态来探测基态，硫K边X射线吸收光谱（XAS）来实验性地定义配体-金属键的共价性，和金属L-边XAS来量化高度共价环境中不同金属d轨道的离域。该研究项目定义了蓝铜蛋白中特定超交换途径的ET效率，并通过实验确定了将其还原电位调节到数百毫伏以上的关键因素。 参与该项目的研究生将蓝铜中硫醚-Cu键的蛋白质控制的最新结果扩展到混合价双核CuA中心和细胞色素c（cyt c）活性位点。 细胞色素c中的铁硫键，它在ET中的作用，以及它在细胞色素c的过氧化物酶活性中在凋亡中的作用也正在研究中。 溶剂调谐的铁-硫蛋白质中的铁-硫键的共价性和蛋白质，DNA，S-腺苷甲硫氨酸，和ATP的结合上的键合的影响进行评估，以确定这些结构如何有助于激活这些集群的不同ET功能。 最后，研究小组通过实验校正了电子结构计算，并使用实验验证的计算来理解氧代-Mo转移酶和非无辜二硫烯连接中的氧代转移过程和质子耦合ET，这项研究对于理解生物学中的电子转移和氧原子转移具有重要意义，并且与人类健康有关这些领域包括生物技术（理解和治疗疾病状态、细胞凋亡和光动力疗法以及DNA修复）、生物技术（氧化还原酶和生物燃料电池）和生物修复（消除温室气体N2 O）。 作为这项研究的一部分开发的新光谱技术允许对适用于许多科学学科的计算方法进行评估。这些方法通过广泛的合作影响生物无机界。 所罗门教授在他的讲座，书籍章节和编辑文本中推广新的和新颖的光谱方法。 还有一个有组织的努力，通过维基百科传播实验室的专业知识。 在社区内，所罗门集团主办海湾地区高中化学教师在夏季研究，并参与建立一个学徒计划与青年赋权机构合作。 该小组促进了少数民族中学生的科学参与。

This award by the Chemical Structure, Dynamics, and Mechanisms (CSDM) Program of the Chemistry Division to Professor Edward I. Solomon of Stanford University supports the use of a wide range of spectroscopic methods coupled with electronic structure calculations to understand the unique spectral features of metalloprotein active sites involved in biological electron transfer (ET) and oxo atom transfer (OAT). Novel active site geometric and electronic structures can make major contributions to reactivity. New spectroscopic methods are developed as part of the program including: variable-temperature, variable-field magnetic circular dichroism (VTVH MCD) to assign electronic transitions and use excited states to probe ground states, sulfur K-edge x-ray absorption spectroscopy (XAS) to experimentally define the covalency of ligand-metal bonds, and metal L-edge XAS to quantify the delocalization of the different metal d orbitals in highly covalent environments. This research project defines the ET efficiencies of specific superexchange pathways in blue copper proteins and experimentally determines the key factors that tune their reduction potentials over hundreds of millivolts. The graduate students involved in the project extend recent results on protein control of the thioether-Cu bond in blue copper to the mixed-valent binuclear CuA center and to cytochrome c (cyt c) active sites. The iron-sulfur bond in cyt c, its contribution in ET, and its role in the peroxidase activity of cyt c in apoptosis is also under study. Solvent tuning of the covalency of iron-sulfur bonds in iron-sulfur proteins and the effects of the protein, DNA, S-adenosylmethionine, and ATP binding on the bonding are evaluated to determine how these structures contribute to the activation of the different ET functions of these clusters. Finally, the research group experimentally calibrates electronic structure calculations and uses experimentally-validated calculations to understand the oxo transfer process and proton coupled ET in the oxo-Mo transferases and in the non-innocent dithiolene ligation.This research is of fundamental importance in understanding electron transfer and oxygen atom transfer in biology and is relevant to human health (understanding and treating disease states, apoptosis and photodynamic therapy, and DNA repair), biotechnology (oxidoreductases and bio-fuel cells), and bioremediation (elimination of the greenhouse gas, N2O). New spectroscopic techniques developed as part of this research allow for the evaluation of computational methods that have applicability across many scientific disciplines. These methods impact the bioinorganic community through a wide range of collaborations. Professor Solomon promotes new and novel spectroscopic methods during his lectures, book chapters, and edited texts. There is also an organized effort to disseminate the laboratory's expertise through Wikipedia. Within the community, the Solomon group hosts Bay Area high school chemistry teachers in summer research and is involved in establishing an apprenticeship program in collaboration with a youth empowerment agency. This group promotes the scientific participation of minority middle school students.