Electron Spin in Metalloprotein Electron Transfer

金属蛋白电子转移中的电子自旋

• 批准号: 6967352
• 负责人: JAMES K MCCUSKER
• 金额: $ 28.84万
• 依托单位: MICHIGAN STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6967352
• 关键词: active sites; chemical kinetics; computational biology; electron transport; emission spectrometry; iron; iron sulfur protein; metalloproteins; oxidizing agents; photochemistry; physical model; porphyrins; reducing agents; structural biology; sulfite reductase

DESCRIPTION (provided by applicant): The presence of multiple electronically coupled metal ions in the active sites of metalloproteins imparts unique character to the electronic structures of such systems. The research described in this proposal will determine the extent to which these electronic features play a role in their function. More specifically, this work will examine the influence of electron spin polarization on electron transfer reactions, in particular those relevant to the active sites of several iron-oxo and iron-sulfur metalloproteins. This will be achieved through a confluence of synthetic, physical, and computational chemistries performed on systems ranging from simple coordination compounds to structural models of active sites to surface-modified iron-sulfur proteins. The research will be developed in several stages. First, building on previous results, several model systems will be synthesized that allow for the modulation of electron spin in a controlled and systematic fashion. Time-resolved spectroscopic studies, in conjunction with variable-temperature magnetic measurements, will then be employed to quantify both the electronic structures and electron transfer kinetics of these systems. These studies will provide the first unambiguous experimental data detailing the influence electron spin polarization has on electron transfer reactions involving biologically important metal clusters. More complex systems will then be pursued including, but not limited to, (1) iron-sulfur/porphyrin assemblies to study electron transfer kinetics in models of sulfite reductase; (2) Ru-modified iron-sulfur proteins (e.g., HiPIP) to assess the role of thermally accessible excited spin states within the active-site cluster for protein-based electron transfer; and (3) donor/cluster/acceptor assemblies to effect through-cluster electron transfer, examining the possible role of spin-state modulation for the gating of electron migration in metalloprotein active sites. This work will significantly advance our understanding of mechanistic issues related to metalloprotein electron transfer through its examination of an intrinsic but unexplored aspect of the electronic structure of their active sites.

描述（由申请人提供）：金属蛋白活性位点中多个电子耦合金属离子的存在赋予此类系统的电子结构独特的特征。本提案中描述的研究将确定这些电子特征在其功能中发挥作用的程度。更具体地说，这项工作将研究电子自旋极化对电子转移反应的影响，特别是与几种铁-氧和铁-硫金属蛋白的活性位点相关的反应。这将通过在从简单的配位化合物到活性位点的结构模型到表面修饰的铁硫蛋白的系统上进行的合成、物理和计算化学的融合来实现。该研究将分几个阶段进行。首先，基于先前的结果，将合成几个模型系统，允许以受控和系统的方式调制电子自旋。然后，时间分辨光谱研究与变温磁测量相结合，将用于量化这些系统的电子结构和电子转移动力学。这些研究将提供第一个明确的实验数据，详细说明电子自旋极化对涉及生物学重要金属簇的电子转移反应的影响。然后将寻求更复杂的系统，包括但不限于（1）铁硫/卟啉组件，以研究亚硫酸盐还原酶模型中的电子转移动力学； (2) Ru 修饰的铁硫蛋白（例如 HiPIP），用于评估活性位点簇内热可接近的激发自旋态对于基于蛋白质的电子转移的作用； (3)供体/簇/受体组件，以实现穿过簇的电子转移，研究自旋态调制对于金属蛋白活性位点电子迁移门控的可能作用。这项工作将通过检查金属蛋白活性位点电子结构的内在但未经探索的方面，显着增进我们对与金属蛋白电子转移相关的机械问题的理解。