ELECTRONIC STRUCTURES OF IRON-SULFUR & RELATED PROTEINS

铁硫的电子结构

• 批准号: 3297186
• 负责人: David A Case
• 金额: $ 9.25万
• 依托单位: SCRIPPS CLINIC AND RESEARCH FOUNDATION
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-04-01 至 1991-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3297186
• 关键词: aconitate hydratase; catalyst; citrates; cobalt; electron spin resonance spectroscopy; electronic spectra; ferredoxin; hemoprotein; metalloproteins; molybdenum; oxidation reduction reaction; protein structure; stoichiometry; sulfite reductase; sulfur compounds; vanadium; zinc

This project involves the use of novel techniques in quantum chemistry to study electronic structure problems at the active sites of iron-sulfur proteins, and of related mixed-metal clusters containing Mo, V, Co or Zn, in addition to iron. The principal goal is to understand the nature of spin-coupling in these systems, and to explore how these couplings influence their oxidation-reduction and catalytic properties. This will be accomplished through systematic variation of geometries in calculations on Heisenberg coupling constants, Mossbauer and electron spin resonance parameters (including g and hyperfine tensors) and electric fields and charge densities. All of the calculations will use the X alpha or local spin density effective potentials. Systems to be studied include: (a) three-iron clusters in both linear and pseudo-cubane geometries that are characteristic of active sites in several ferredoxins and in aconitase; (b) four-iron clusters that can exist in multiple oxidation states, with special attention paid to geometries that might allow intermediate or high-spin ground states; (c) models for four-iron clusters linked to a siroheme (as a model for sulfite reductase) or to citrate (as a model for an intermediate step in aconitase); (d) mixed metal clusters with XFe3 stoichiometries (X=Mo, V, Co, Zn), which are implicated in nitrogenase activity or which form useful test systems for our understanding of the active sites of iron-sulfur proteins in general.

该项目涉及在量子中使用新技术 化学以研究主动的电子结构问题 铁硫蛋白和相关混合金属簇的位点 除铁外，还含有Mo，V，Co或Zn。 主要目标 是要了解这些系统中自旋耦合的性质，并且 探索这些耦合如何影响减少氧化的氧化 和催化特性。 这将通过 海森堡计算中几何形状的系统变化 耦合常数，Mossbauer和Electron旋转共振 参数（包括G和超细张量）和电场 并充电。 所有计算将使用x alpha 或局部自旋密度有效电位。 要研究的系统包括：（a）两者中的三个铁簇 线性和伪基的几何形状是特征的 在几种铁蛋白和丙氧酶中的活性位点； （b）四铁 可以在多种氧化状态中存在的簇，具有特殊 注意可能允许中间或 高旋转基态； （c）链接到的四铁簇的模型 Siroheme（作为亚硫酸盐还原酶的模型）或柠檬酸盐（作为A 在刺刺酶中的中间步骤的模型）； （d）混合金属 带有XFE3 stoichiomerties的簇（X = Mo，V，Co，Zn）， 与氮酶活性有关或形成有用的测试 我们了解铁硫的活性位点的系统 蛋白质一般。