細菌の光採集複合体における結合カロテノイドに関する量子化学の研究
1Department of Chemistry, University of Toledo, Toledo, Ohio 43606, USA.
Journal of the American Chemical Society
|July 11, 2002
まとめ
カロテノイドは,芳香質残留物とのpi-piスタッキング相互作用を通じて,光合成タンパク質に結合する. 分散力によって支配されるこれらの相互作用は,光採集複合体内のカロテノイドの安定化に不可欠です.
科学分野:
- バイオケミストリー バイオケミストリー
- 構造生物学 構造生物学とは
- コンピューティング・ケミストリー
背景:
- カロチノイドは,光合成における光の収集と光保護に不可欠です.
- 光合成タンパク質におけるカロテノイド結合の正確な分子機構は,ほとんど不明のままである.
研究 の 目的:
- 光合成性染色体-タンパク質複合体内のカロテノイド結合の分子基盤を解明する.
- 光採集複合体II (LH-II) のカロテノイド安定化におけるpi-piスタッキング相互作用の役割を調査する.
主な方法:
- 光合成性ピグメント-タンパク質複合体の結晶構造の分析.
- MP2メソッドを用いたハイレベルアビニシオ電子構造計算.
- 改変した6-31G*(0.25) ベースセットによる分子間相互作用エネルギーの計算.
主要な成果:
- カロテノイドは,既知の構造において,アロマティック残留物やクロロフィールに常に囲まれています.
- 計算により,LH-II.5.6におけるカロテノイドと芳香質残留物の間の安定化エネルギーが -15.66 kcal/molであることが明らかになった.
- 散乱力は,ピ・ピ・スタッキング相互作用における支配的な吸引力として特定され,有意な静電的貢献があった.
結論:
- カロテノイドとアロマティック残留物の間のPi-piスタッキング相互作用は,Rhodospirillum molischianumのLH-II複合体におけるカロテノイド結合に不可欠である.
- これらの相互作用は,主に分散力によって引き起こされ,色素-タンパク質複合体の安定性におけるそれらの重要性を強調しています.
さらに関連する動画
09:49Investigation of Microbial Cooperation via Imaging Mass Spectrometry Analysis of Bacterial Colonies Grown on Agar and in Tissue During Infection
Published on: November 18, 2022
06:39Analysis of Protein Complex Formation at Micromolar Concentrations by Coupling Microfluidics with Mass Photometry
Published on: January 26, 2024
関連する概念動画
The Equilibrium Binding Constant and Binding Strength
The equilibrium binding constant (Kb) quantifies the strength of a protein-ligand interaction. Kb can be calculated as follows when the reaction is at equilibrium:
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...
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...
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...
Channel Rhodopsins
Most organisms use photoreceptors to sense and respond to light. Examples of photoreceptors include bacteriorhodopsins and bacteriophytochromes in some bacteria, phytochromes in plants, and rhodopsins in the photoreceptor cells of the vertebral retina. The light-sensitive property of these receptors is because of the bound chromophores, such as bilin in the phytochromes and retinal in the rhodopsins.
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
UV–Vis Spectroscopy of Conjugated Systems
Organic compounds with conjugated double bonds show strong absorption features in the UV–visible region of the electromagnetic spectrum attributed to π → π* electronic excitations. Generally, a UV–vis absorption spectrum is recorded as a plot of absorbance vs wavelength. The wavelength of maximum absorbance, which manifests as a peak in the absorption spectrum, is denoted as λmax.
One of the factors influencing λmax is the extent of conjugation in the...
One of the factors influencing λmax is the extent of conjugation in the...
