切换氧化还原机制:从氨酸和氨酸中进行质子合电子转移的模型
Martin Sjödin1, Stenbjörn Styring, Henriette Wolpher
1Department of Physical Chemistry, BMC, Uppsala University, PO Box 579, SE-751 23 Uppsala, Sweden.
Journal of the American Chemical Society
|March 18, 2005
概括
在模型系统中,质子合电子转移 (PCET) 可以通过阶段性 (ETPT) 或协调 (CEP) 机制发生. 研究人员确定了控制这些途径的因素,发现CEP可能对某些反应产生影响.
科学领域:
- 生物化学 生物化学
- 物理化学 物理化学
- 摄影化学的使用.
背景情况:
- 质子合电子转移 (PCET) 在生物系统如光系统II中至关重要.
- 了解PCET机制是破译激素蛋白功能的关键.
研究的目的:
- 在涉及氧化氨酸或氨酸的模型复合体中研究PCET.
- 分析逐步 (ETPT) 和协调 (CEP) 反应途径之间的竞争.
主要方法:
- 采用激光闪光光溶解产生一个trisbipyridine-Ru(III) 氧化剂.
- 应用了马库斯关于电子转移的理论来分析动力数据.
- 操纵溶液的pH值,氧化剂强度和氨基酸身份,以控制反应机制.
主要成果:
- 确定了有利于ETPT或CEP机制的条件.
- 量化参数影响每个路径的主导地位.
- 与ETPT相比,CEP观察到更高的重组能量和动态同位素效应.
结论:
- 协同 PCET 是一个可能的途径,特别是在弱异能反应.
- 驱动力和重组能量之间的相互作用决定了主导机制.
- 动态同位素效应证实了CEP的速度决定步骤中的显著质子运动.
相关概念视频
Redox Reactions
Oxidation-reduction or redox reactions involve the transfer of electrons from one molecule or atom to another. When an atom gains an electron, another atom must lose an electron, meaning oxidation and reduction must occur together. Since the redox occurs in pairs, the atom that gets oxidized is also called the reducing agent or reductant, and the atom that is reduced is also called the oxidizing agent or oxidant. A straightforward way to remember the definitions of oxidation and reduction is...
Electron Transport Chains
The final stage of cellular respiration is oxidative phosphorylation that consists of two steps: the electron transport chain and chemiosmosis. The electron transport chain is a set of proteins found in the inner mitochondrial membrane in eukaryotic cells. Its primary function is to establish a proton gradient that can be used during chemiosmosis to produce ATP and generate electron carriers, such as NAD+ and FAD, that are used in glycolysis and the citric acid cycle.
The ETC is comprised of...
The ETC is comprised of...
The Electron Transport Chain
The electron transport chain or oxidative phosphorylation is an exothermic process in which free energy released during electron transfer reactions is coupled to ATP synthesis. This process is a significant source of energy in aerobic cells, and therefore inhibitors of the electron transport chain can be detrimental to the cell's metabolic processes.
Inhibitors of the electron transport chain
Rotenone, a widely used pesticide, prevents electron transfer from Fe-S cluster to ubiquinone or Q in...
Inhibitors of the electron transport chain
Rotenone, a widely used pesticide, prevents electron transfer from Fe-S cluster to ubiquinone or Q in...
Oxidation and Reduction of Organic Molecules
Energy production within a cell involves many coordinated chemical pathways. Most of these pathways are combinations of oxidation and reduction reactions, which occur at the same time. An oxidation reaction strips an electron from an atom in a compound, and the addition of this electron to another compound is a reduction reaction. Because oxidation and reduction usually occur together, these pairs of reactions are called redox reactions.
The removal of an electron from a molecule, results in a...
The removal of an electron from a molecule, results in a...
Redox Equilibria: Overview
A reduction-oxidation reaction is commonly called a redox reaction. In a redox reaction, electrons are transferred from one species to another rather than being shared between or among atoms. The reducing agent or reductant is the species that loses electrons and gets oxidized in the process. The species that gains electrons and gets reduced in the process is the oxidizing agent or oxidant. Redox reactions are represented as two separate equations called half-reactions, where one equation...
Processes at Electrodes
The electrode interacts with ions in the electrolyte solution at its interface. The rate of oxidation and reduction depends on the speed at which electrons can transfer through this interface. As ions attach to or leave the electrode surface, the electrode acquires a charge, and an electrical potential forms across the interface, making the process more difficult to reach equilibrium. The charge on the electrode affects the local ion concentrations in the solution, though thermal motion...


