溶液中の11-cis網膜プロトネートシフ基のバリアレス光異性化
Giovanni Bassolino1, Tina Sovdat2, Alex Soares Duarte1
1Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford , South Parks Road, Oxford OX1 3QZ, U.K.
Journal of the American Chemical Society
|September 17, 2015
まとめ
主な視覚的イベントは,超高速の網膜陽子シフ基 (RPSB) フォトイソメリゼーションを含む. この研究は,バリアレス光異性化がタンパク質に依存するだけでなく,RPSBの固有の特性であることを明らかにしています.
科学分野:
- 写真化学
- 分子生物学
- 視覚科学
背景:
- 視覚性染色体ロドプシンの機能は,網膜のプロトン化シフ基 (RPSB) 染色体の11-cisから全トランスフォトイソメリゼーションに依存する.
- この超高速で効率的な反応は 主要な視覚現象の特徴と考えられています
- ロドプシン内のクロモフォールタンパク質の相互作用は,潜在エネルギー表面を修正し,この驚くべき反応性を可能にすると考えられています.
研究 の 目的:
- 11-cis RPSBの固有の特性であるかどうかを調査する.
- RPSBの光化学を調節するタンパク質環境の役割を決定する.
主な方法:
- 合成と超高速スペクトロスコピーの組み合わせが採用された.
- 研究は11-cis RPSB染色体の固有特性に焦点を当てた.
主要な成果:
- 11- cis RPSBの固有の特性として,バリアレス光異性化が確認された.
- タンパク質環境は,主に興奮状態の異なる分解経路のバランスを調節する可能性があります.
結論:
- RPSBの内在的な反応性は,バリアのない異体化を促進するよりも,ロドプシンが反応チャネルを微調整する役割を果たす可能性があることを示唆している.
- これらの発見は,RPSBの光化学と視覚におけるその役割を記述する現在のモデルの再評価を必要とします.
さらに関連する動画
関連する概念動画
01:26Photochemical Electrocyclic Reactions: Stereochemistry
2.4K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
2.4K
01:22Photoreceptors and Visual Pathways
11.1K
At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category,...
11.1K
01:27Photosystem I
71.8K
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...
71.8K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
3.2K
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
3.2K
01:22Photosystem II
80.6K
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...
The pigment molecules are arranged across two photosystem domains — the antenna complex and the reaction center. The main aim of the pigment...
80.6K
01:29The Photochemical Reaction Center
5.9K
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...
5.9K