エネルギー伝達の構造ベースのモデルは,光システムIIの超複合体における光の収穫の原理を明らかにする
Doran I G Bennett1, Kapil Amarnath, Graham R Fleming
1Department of Chemistry, University of California, Berkeley, California 94720, USA.
Journal of the American Chemical Society
|May 18, 2013
まとめ
フォトシステムII (PSII) の光採集は複雑で,速度を制限する単一のステップはありません. 私たちのモデルは,PSII超複合体におけるエネルギー転送を明確にし,光データ解釈を改善します.
科学分野:
- 植物生物学 植物生物学
- 光合成研究 研究 光合成研究
- バイオフィジックス 生物物理学
背景:
- 光システムII (PSII) は,電荷分離を通じて光エネルギーを化学エネルギーに変換することによって光合成を推進します.
- 光集積複合体II (LHCII) トリマーを含むPSII超複合体は,植物グラーナ膜の効率的な光吸収に不可欠である.
研究 の 目的:
- PSIIスーパーコンプレックス内のエネルギー転送のための最初の構造ベースのモデルを開発する.
- PSIIにおける高効率の光採集の基礎となるメカニズムを定量的に分析する.
主な方法:
- PSII超複合体におけるエネルギー転送のための新しい構造ベースの計算モデルを構築.
- 興奮拡散の分析とアンテナから反応センターへの転送運動.
主要な成果:
- このモデルは,PSIIにおける光採集運動は,単一のステップによって制限されないことを明らかにしています.
- アンテナのピグメントを通しての刺激拡散と反応センターへの転送の両方が,エネルギー伝送に大きく貢献します.
- 速度制限ステップの欠如は,機械的洞察のための光寿命データの解釈に挑戦しています.
結論:
- 開発されたモデルは,PSIIにおける複雑なエネルギー転送経路を理解するための枠組みを提供します.
- それは,PSIIの光採集効率を説明する簡略化された運動モデルの限界を強調しています.
- この研究は,様々な植物構造から得られたクロロフィルの光データに関する解釈を強化します.
関連する概念動画
01:22Photosystem 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...
01:27Photosystem 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...
01:15The 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...
01:32Photosystems
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...
01:34The 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...
01:29The 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...