結晶や電極膜におけるインターフェイスタンパク質の電子移転に対する溶媒同位体効果
Seong A Kang1, Kevin R Hoke, Brian R Crane
1Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
Journal of the American Chemical Society
|February 16, 2006
まとめ
酸化デウテリウム (D2O) がシトクロームc過酸化酵素 (CcP) の結晶に置換されると,電子移転 (ET) の運動が遅くなる. このD2O効果は,結晶とフィルムの両方の研究で観察され,CcP-cytochrome c相互作用に影響を与えるゆっくり交換する陽子または溶媒分子に起因する.
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
- 物理化学 物理化学について
背景:
- サイトクロームc過酸化酵素 (CcP) とサイトクロームc (yCc) は,細胞呼吸における重要な酵素である.
- CcPとyCcの間の電子移転 (ET) は,それらの機能にとって極めて重要です.
- ET率に影響を与える要因を理解することは,生化学および生理学的研究にとって不可欠です.
研究 の 目的:
- デウテリウム酸化物 (D2O) 置換による酵母単一サイトクロームcペロキシダース (ZnCcP) と酵母単一サイトクロームc (yCc) 複合体の構造と電子伝送動力学への影響を調査する.
- タンパク質とタンパク質の相互作用と電子伝送経路の調節におけるD2Oの役割を明らかにする.
主な方法:
- 高解像度構造を決定するために,D2Oで育ったZnCcP-yCc結晶のX線結晶学.
- 電子移転 (ET) とトリプル興奮状態の滅を測定するためのスペクトル解析.
- タンパク質膜電圧測定は,電極表面上の yCc フィルムのET 速度を評価するために行われます.
主要な成果:
- D2Oで育った結晶は,より高い解像度 (1.7 Å) に微分され,H2Oで育った結晶と比べて異なる包装を示しました.
- 2つのZnCcP分子が1つのyCcに結合し,ZnCcPからFe(III) yCc (k(e) =220s−1) へのETが観察されました.
- D2O置換は,結晶における熱再結合ETと,yCc膜における電子移転を著しく遅らせ,同位体効果が観察された.
結論:
- D2O置換は,yCcとCcPまたは電極膜の間の相互作用と電子転送を乱します.
- 観測された効果は,ゆっくりと交換される陽子や溶媒分子に起因し,微妙な構造変化をもたらします.
- これらの発見は,同位体環境に対する電子転送プロセスの感受性を強調しています.
関連する概念動画
Intermolecular Forces
Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions (attractive or repulsive) between charged species (permanent, partial, or temporary charges) and exist with varying strengths between ions, polar, nonpolar, and neutral molecules. The different types of intermolecular forces are ion–dipole, dipole–dipole, hydrogen bonds, and dispersion; among these, dipole–dipole, hydrogen bonds, and dispersion...
Protein Diffusion in the Membrane
Proteins show rotational as well as lateral diffusion across the membrane. The lateral diffusion of proteins was confirmed through the cell fusion experiment where mouse and human cells were fused, resulting in hybrid cells. When the human and mouse cells fused, the specific membrane proteins on human and mouse cells were marked with the red and green-fluorescent markers, respectively. Initially, the red and green fluorescence was located on the respective hemisphere of the cell. As time...
Potentiometry: Membrane Electrodes
Membrane electrodes, also known as p-ion electrodes, use membranes that selectively interact with free analyte ions, generating a potential difference across the membrane. The resulting membrane potential, known as the asymmetry potential, is not zero even when analyte concentrations on both sides of the membrane are equal. The membrane's response is typically not selective to a single analyte but proportional to the concentration of all ions in the sample solution capable of interacting at the...
Theory of Strong Electrolytes
The interionic forces of the strong electrolytes depend on the solvent's dielectric constant, which is the ability of a solvent to store electrical energy, based on its polarizability. and the solution's concentration. In high-dielectric solvents and in dilute solutions, weak electrostatic forces keep ions apart. However, in low-dielectric solvents or concentrated solutions, stronger interionic forces may cause ions to pair up as ionic doublets despite being fully ionized. The theory of strong...
Electrochemical Systems
Electrochemical systems provide a fascinating insight into the dynamic interplay of charged species within various phases. One notable example is the interaction between a membrane permeable to K⁺ ions but not to Cl⁻ ions, separating an aqueous KCl solution from pure water. As K⁺ ions diffuse through the membrane, they generate net charges on each phase, leading to a potential difference between them.Similarly, when a piece of Zn is immersed in an aqueous ZnSO₄ solution, the Zn metal, composed...
The Electrical Double Layer
In the region where two bulk phases meet, an intricate electric charge distribution arises due to charge transfer, ion adsorption, molecular orientation, and charge distortion. This complex distribution is commonly referred to as the electrical double layer.When a solid electrode interfaces with ions in an electrolyte solution, the speed of electron transfer dictates the rates of oxidation and reduction. The electrode acquires a charge through the escape of atoms into the solution as cations or...


