![Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F55858.jpg&w=3840&q=50)
洞察蛋白质中的 [4Fe-4S] 集群对 [4Fe-4S] 集群的结合和氧化还原特性对环境的影响
1Department of Chemistry, Georgetown University, Washington, DC 20057-1227, USA.
Journal of the American Chemical Society
|April 4, 2009
概括
蛋白质连接体构造,而不是键,显著改变了HiPIPs和ferredoxins中的铁-硫聚合潜力. 这种形状效应为调整氧化还原潜力提供了一个新的机制.
科学领域:
- 生物有机化学 生物有机化学
- 计算化学计算化学
- 蛋白质光谱学 蛋白质光谱学
背景情况:
- 高铁硫蛋白 (HiPIPs) 和铁素表现出与蛋白质和溶剂相互作用有关的独特的氧化还原潜力.
- 之前的研究表明,键会影响这些蛋白质的Fe-S共价性和氧化还原调.
研究的目的:
- 调和关于键与静电效应在调整 [4Fe-4S] 集群氧化还原潜力中的作用的相互矛盾的发现.
- 为了研究连接体构成对HiPIPs和ferredoxins之间的氧化还原潜力差异的贡献.
主要方法:
- 密度函数理论 (DFT) 的计算被用来建模 [4Fe-4S] 集群.
- 分析了光电子光谱数据与DFT结果结合.
- 电子结构的比较和计算的氧化还原潜力基于不同的连接体构造.
主要成果:
- 观察到的Fe-S共价性差异主要是由于连接体构成的变化,而不是键.
- 发现联结体构成可调节计算的氧化还原电位大约100mV.
- DFT研究成功地合理化了关于共价性和静电调的实验发现.
结论:
- 蛋白质连接体构成是调整 [4Fe-4S] 集群的氧化还原潜力的重要,以前没有考虑的因素.
- 键的静电效应起着作用,但形状变化是主要的调整机制.
- 这项研究为对HiPIPs和ferredoxins的实验观察提供了统一的解释.
相关概念视频
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
02:32Bonding in Metals
Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Drüde called the “Electron Sea Model”.
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
01:30Ladder Diagrams: Redox Equilibria
Ladder diagrams are useful tools for understanding redox equilibrium reactions, especially the effects of concentration changes on the electrochemical potential of the reaction. The vertical axis in the redox ladder diagrams represents the electrochemical potential, E. The area of predominance is demarcated using the Nernst equation.
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...