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

电子结构对电子转移和氧原子转移贡献的光谱阐明

• 批准号: 0948211
• 负责人: Edward Solomon
• 金额: $ 73.95万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0948211&HistoricalAwards=false
• 关键词: Spectroscopic; Elucidation; Electronic; Structure; Contributions

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.

这一奖项由化学系化学结构、动力学和机制(CSDM)计划授予斯坦福大学的Edward I.所罗门教授，支持使用广泛的光谱方法结合电子结构计算来了解参与生物电子转移(ET)和氧原子转移(OAT)的金属蛋白活性中心的独特光谱特征。新颖的活性中心几何结构和电子结构对反应活性有重要贡献。作为程序的一部分，开发了新的光谱方法，包括：变温变场磁性圆二色谱(VTVHMCD)用于指定电子跃迁并使用激发态探测基态，硫K边X射线吸收光谱(XAS)用于实验定义配体-金属键的共价性，以及金属L边XAS用于量化不同金属d轨道在高共价环境中的离域。这项研究项目定义了蓝铜蛋白中特定超交换途径的ET效率，并通过实验确定了使其还原电位超过数百毫伏的关键因素。参与该项目的研究生将蓝铜中硫醚-铜键的蛋白质控制的最新结果扩展到混价双核CUA中心和细胞色素c(Cytc)活性部位。细胞色素C中的铁硫键、它在内质网中的作用，以及它在细胞凋亡中的过氧化物酶活性中的作用也在研究中。评估了铁硫蛋白中铁-硫键共价性的溶剂调节以及蛋白质、脱氧核糖核酸、S-腺苷蛋氨酸和三磷酸腺苷结合对铁硫键的影响，以确定这些结构如何有助于激活这些簇的不同ET功能。最后，该研究小组通过实验校准电子结构计算，并使用实验验证的计算来了解氧-钼转移酶和非无害的二硫烯连接中的氧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，并与人类健康(了解和治疗疾病状态、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N2O)有关。作为这项研究的一部分开发的新光谱技术允许评估具有跨许多科学学科适用性的计算方法。这些方法通过广泛的合作影响了生物无机界。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。还有一项有组织的努力，通过维基百科传播该实验室的专业知识。在社区内，所罗门小组接待湾区高中化学教师进行暑期研究，并参与与青年赋权机构合作建立学徒计划。这个群体促进了少数民族中学生的科学参与。