基于光系统光学光谱的结构计算,我建议一个不对称的光收获过程
Julian Adolphs1, Frank Müh, Mohamed El-Amine Madjet
1Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstrasse 36a, D-14195 Berlin, Germany.
Journal of the American Chemical Society
|February 20, 2010
概括
本研究使用量子化学计算模拟光系统I的光学光谱. 研究结果揭示了影响色素-蛋白质能量传递的远程静电相互作用,这表明光合作用过程中的光采集不对称.
科学领域:
- 光合作用研究研究光合作用.
- 量子化学是一种量子化学.
- 频谱学是一种光谱学.
背景情况:
- 光系统I (PSI) 对于光合作用中的光采集和电子转移至关重要.
- 了解PSI中的色素蛋白相互作用是阐明能量转移机制的关键.
研究的目的:
- 为了模拟Thermosynechococcus elongatus光系统I核心复合物的光学光谱.
- 分析色素-蛋白相互作用和能量传输途径.
主要方法:
- 结合光学线形状理论与量子化学/静电计算.
- 计算了96 种叶绿素a 颜料的位点能量和刺激性合.
- 使用2.5 Å晶体结构进行光谱模拟.
主要成果:
- 模拟的吸收率,线性二元化和圆形二元化光谱与实验数据半定量匹配.
- 证明了远程静电相互作用 (>20个氨基酸残留物) 在确定色素位点能量中的重要作用.
- 确定了反应中心附近的低能激子状态和有利于A分支的不对称分布.
结论:
- 该研究强调了静电相互作用在PSI功能中的重要性.
- 刺激子状态的不对称分布表明,一种机制可以向反应中心的一个分支提供优先的能量.
- 这种不对称性可能解释了反应中心分支在电子转移中的差异性使用.
相关概念视频
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...
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...
Photosystems
Photosystems are multiprotein complexes that form the functional units of photosynthesis in plants, algae, and cyanobacteria. They are found embedded in the membrane of tiny sac-like structures called thylakoids placed inside the chloroplast.
Functioning of Photosystems
Photosystems contain many pigment molecules, such as chlorophylls and carotenoids, arranged in a particular organization across two domains — the antenna complex and the reaction center. The main aim of the pigment molecules...
Functioning of Photosystems
Photosystems contain many pigment molecules, such as chlorophylls and carotenoids, arranged in a particular organization across two domains — the antenna complex and the reaction center. The main aim of the pigment molecules...
The Antenna Complex
Plants and other photosynthetic organisms comprise pigments capable of absorption of direct sunlight. These pigments are present in the reaction center - the main site of photochemical reactions as well as in the antenna complex. Under average light conditions, the rate at which reaction center pigments absorb light is far below the electron transport chain's capacity. As a result, the reaction center alone cannot provide enough energy to drive photosynthesis. The photosynthetic efficiency can...
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...
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...

