Becucci Lucia, Guidelli Rolando
Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia, 3, Sesto Fiorentino 50019, Italy.
Membranes (Basel). 2016 Dec 13;6(4):53. doi: 10.3390/membranes6040053.
The functional activity of channel-forming peptides and proteins is most directly verified by monitoring the flow of physiologically relevant inorganic ions, such as Na⁺, K⁺ and Cl, along the ion channels. Electrical current measurements across bilayer lipid membranes (BLMs) interposed between two aqueous solutions have been widely employed to this end and are still extensively used. However, a major drawback of BLMs is their fragility, high sensitivity toward vibrations and mechanical shocks, and low resistance to electric fields. To overcome this problem, metal-supported tethered BLMs (tBLMs) have been devised, where the BLM is anchored to the metal via a hydrophilic spacer that replaces and mimics the water phase on the metal side. However, only mercury-supported tBLMs can measure and regulate the flow of the above inorganic ions, thanks to mercury liquid state and high hydrogen overpotential. This review summarizes the main results achieved by BLMs incorporating voltage-gated channel-forming peptides, interpreting them on the basis of a kinetic mechanism of nucleation and growth. Hg-supported tBLMs are then described, and their potential for the investigation of voltage-gated and ohmic channels is illustrated by the use of different electrochemical techniques.
通过监测生理相关无机离子（如Na⁺、K⁺和Cl）沿离子通道的流动，可以最直接地验证形成通道的肽和蛋白质的功能活性。为此，测量跨置于两种水溶液之间的双层脂质膜（BLM）的电流已被广泛应用，并且仍在广泛使用。然而，BLM的一个主要缺点是其易碎性、对振动和机械冲击的高敏感性以及对电场的低抗性。为了克服这个问题，人们设计了金属支撑的拴系BLM（tBLM），其中BLM通过一个亲水性间隔物锚定在金属上，该间隔物取代并模拟了金属一侧的水相。然而，由于汞的液态和高氢过电位，只有汞支撑的tBLM能够测量和调节上述无机离子的流动。本综述总结了包含电压门控通道形成肽的BLM所取得的主要成果，并根据成核和生长的动力学机制对其进行了解释。然后描述了汞支撑的tBLM，并通过使用不同的电化学技术说明了它们在研究电压门控通道和欧姆通道方面的潜力。
