基于EXAFS模拟的结构精细化预测的光系统II的氧气进化中心模型
Eduardo M Sproviero1, José A Gascón, James P McEvoy
1Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, USA.
Journal of the American Chemical Society
|May 7, 2008
概括
光系II (PSII) 中的氧进化复合体 (OEC) 的新计算模型揭示了Mn3CaO4核心与悬挂的Mn. 这种结构与实验数据保持一致,有助于理解水分裂机制.
科学领域:
- 生物化学 生化学
- 结构生物学 结构生物学
- 光合作用研究研究 光合作用研究
背景情况:
- 光系统II (PSII) 中的氧进化复合体 (OEC) 对于光合作用至关重要.
- 了解OEC的精确结构是阐明水分裂机制的关键.
研究的目的:
- 在PSII.II中引入OEC的精细计算结构模型.
- 提出一个与现有实验数据相一致的模型.
- 为进一步研究水分机制提供一个工具.
主要方法:
- 计算建模计算建模
- 对X射线衍射 (XRD) 模型的分析.
- 高分辨率光谱数据的解释 (偏振和同向型EXAFS)
主要成果:
- 建议采用立方形的Mn3CaO4核心,其中一个"危险"的Mn与一个角 mu4-氧化物离子结合在一起.
- 这个模型证明了在金属集群周围氨基酸定位的最大一致性.
- 该模型与定向单晶的极化EXAFS和同位素EXAFS数据保持一致.
结论:
- 精细的结构模型为理解OEC提供了一个强大的框架.
- 预计该模型将有助于确定OEC结构.
- 它将有助于阐明PSII中的水分裂机制,包括中间氧化状态.
相关概念视频
Photosystem II
The multi-protein complex photosystem II (PS II) harvests photons and transfers their energy through its bound pigments to its reaction center, and ultimately to photosystem I (PSI) through the electron transport chain. The pigments responsible for caputirng the light energy in photosystems include chlorophyll a, chlorophyll b, and carotenoids.
The pigment molecules are arranged across two photosystem domains — the antenna complex and the reaction center. The main aim of the pigment molecules...
The pigment molecules are arranged across two photosystem domains — the antenna complex and the reaction center. The main aim of the pigment molecules...
The Photochemical Reaction Center
Reaction centers are pigment-protein complexes that initiate energy conversion from photons to chemical entities. Therefore, photochemical reaction center is a more appropriate term that describes these complexes. The Nobel laureates Robert Emerson and William Arnold provided the first experimental evidence of photochemical reaction centers by demonstrating the participation of nearly 2,500 chlorophyll molecules for the release of just one molecule of oxygen. Despite thousands of photosynthetic...
Oxygenic Photosynthesis
Oxygenic photosynthesis is a fundamental process in which light energy is harnessed to drive the oxidation of water, leading to the production of molecular oxygen (O₂), adenosine triphosphate (ATP), and nicotinamide adenine dinucleotide phosphate (NADPH). This process is essential for sustaining aerobic life on Earth and is primarily carried out by cyanobacteria, algae, and plants. The core of oxygenic photosynthesis lies in the thylakoid membranes, where chlorophyll pigments facilitate light...
Photosystem I
Although structurally similar to photosystem II (PSII), photosystem I (PSI) is has a different electron supplier and electron acceptor.
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...
The Z-Scheme of Electron Transport in Photosynthesis
The light reactions of photosynthesis assume a linear flow of electrons from water to NADP+. During this process, light energy drives the splitting of water molecules to produce oxygen. However, oxidation of water molecules is a thermodynamically unfavorable reaction and requires a strong oxidizing agent. This is accomplished by the first product of light reactions: oxidized P680 (or P680+), the most powerful oxidizing agent known in biology. The oxidized P680 that acquires an electron from the...
ATP Synthase: Structure
ATP synthase or ATPase is among the most conserved proteins found in bacteria, mammals, and plants. This enzyme can catalyze a forward reaction in response to the electrochemical gradient, producing ATP from ADP and inorganic phosphate. ATP synthase can also work in a reverse direction by hydrolyzing ATP and generating an electrochemical gradient. Different forms of ATP synthases have evolved special features to meet the specific demands of the cell. Based on their specific feature, ATP...


