ナトリウムイオンは,脂質二重層の中でどのくらいの距離を移動することができますか?

François Otis¹, Charles Racine-Berthiaume, Normand Voyer

¹Département de Chimie and PROTEO, Faculté des Sciences et de Génie, Université Laval, Pavillon Alexandre-Vachon, 1045 avenue de la Médecine, Québec, QC, Canada, G1V 0A6.

Journal of the American Chemical Society

|March 10, 2011

まとめ

研究者は,膜内のカチオン輸送を理解するために,合成イオンチャネルを探索しました. 彼らは,ナトリウムイオンが,脂質二重層内の結合部位間で最大11 Åの距離を移動できることを発見しました.

科学分野:

生物物理化学生物物理化学とは
膜バイオフィジックス
超分子化学とは

背景:

合成イオンチャネルは,生物膜の間のイオン輸送を理解するために不可欠です.
螺旋状ペプチドは,人工イオンチャネルを設計するための有望な支架を提供します.
クラウンエーサーはイオン結合部位として作用し,イオン転位を促進します.

研究の目的:

合成イオンチャネルを通じたカチオン転位のメカニズムを調査する.
脂質二重層環境内のイオンリレーの最適な距離を決定する.
異なるクラウンエーテル改変による新しいヘリクル状ペプチドアナログの合成と特徴付け.

主な方法:

2,3,4,6クラウンエーテル単位で機能化されたヘリコペプチドアナログの合成.
電気生理学的技術を用いて,人工脂質二重層の間のイオン輸送を測定する.
合成アナログの構造と完全性を確認するためのスペクトル解析.

主要な成果:

合成されたアナログは,脂質二重層にわたってカチオンを輸送するさまざまな能力を示しました.
クラウンエーテル単位数とイオン輸送効率の間の相関が観察されました.
脂質二重層内の結合部位間のナトリウムイオントランスロケーションの最大有効距離は11 Åであると決定されました.

結論:

この研究は,合成イオンチャネルにおけるカチオン転位の距離制約を解明しています.
冠エーテルリレーを備えた螺旋ペプチドベースのイオンチャネルは,膜輸送を研究するためのモデルシステムを提供します.
発見は,センシングと分離における潜在的なアプリケーションのための人工イオンチャネルの合理的な設計に貢献します.

さらに関連する動画

05:27

Inner Mitochondrial Membrane Sensitivity to Na⁺ Reveals Partially Segmented Functional CoQ Pools

Published on: July 20, 2022

10:22

Reconstitution of a Kv Channel into Lipid Membranes for Structural and Functional Studies

Published on: July 13, 2013

関連する概念動画

01:24

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...

01:12

Diffusion

Diffusion is the passive movement of substances down their concentration gradients—requiring no expenditure of cellular energy. Substances, such as molecules or ions, diffuse from an area of high concentration to an area of low concentration in the cytosol or across membranes. Eventually, the concentration will even out, with the substance moving randomly but causing no net change in concentration. Such a state is called dynamic equilibrium, which is essential for maintaining overall...

01:23

Drug Absorption Mechanism: Passive Membrane Transport

Passive transport is a method of drug absorption where small, lipid-soluble drugs can move across the cell membrane. This movement happens along the concentration gradient, which is a natural flow from higher to lower concentration areas. The speed at which the drug moves is directly related to its lipid–water partition coefficient. This means that the more a drug dissolves in lipids, the faster it diffuses or spreads throughout the body. It is important to note that most drugs are either weak...

01:35

Asymmetric Lipid Bilayer

Biological membranes show uneven distribution of different types of lipids in the inner and outer layers, resulting in transverse asymmetric membranes. The treatment of the erythrocyte membrane with the enzyme phospholipase confirmed the asymmetric nature of the lipid bilayer. The enzyme hydrolyzes lipids into fatty acids and hydrophilic groups. The phospholipase acts only on the outer layer of the membrane, while the inner layer remains intact. The phospholipase treatment resulted in 80%...

01:44

The Significance of Membrane Transport

The transport of solutes across the cell membrane is essential for metabolic processes, like maintaining cell size and volume, generating the action potential, exchanging nutrients and gases, etc. Membrane transport can be either passive or active. It can be simple diffusion, facilitated, or mediated transport aided by transport proteins such as transporters and channels.
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...

01:17

Pore Transport and Ion-Pair Transport

Pore transport and ion-pair formation are critical mechanisms for the absorption and distribution of drugs in the body.
Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct microscopic...

関連する実験動画