PHYSICS OF IONIC CHANNELS AND OTHER PROTEINS WITH AQUEOUS CAVITIES

我们分析了电压依赖的信号转导特性 在存在外部电噪声源的情况下的离子通道。 实验是用丙氨西林修饰的平面脂质双层进行的 一种研究得很好的通道形成肽。电流对一个小的 测量了不同掺杂量的正弦波电压信号。 “白”噪音。我们证明了在该系统中添加外部噪声 输入导致其输出端的信号分量显著增加。 这种由噪声引起的信号传递增强并不会减少 输出信噪比，并显示了 随机共振。 正如我们之前通过使用不同的磷脂物种所显示的 倾向于形成非片层结构，阿米西林通道为 对膜脂包装的固有应力敏感。我们 能够定量地关联河道构象平衡 从其对膜填料的开闭统计中可见 能量学。这是通过对统计学的研究来实现的 带电脂质包结丙氨西林通道的特性 薄膜。在这些实验中，每个脂质分子的电荷发生了变化。 通过改变膜浴溶液的pH值。

We have analyzed the signal transduction properties of voltage dependent ion channels in the presence of an external electric noise source. Experiments were done with planar lipid bilayers modified by alamethicin a well studied channel-forming peptide. A current response to a small sine-wave voltage signal was measured at different levels of admixed "white" noise. We showed that addition of external noise to this system input induces a significant increase of signal component at its output. This noise-induced enhancement in signal transductiion does not decrease the output signal-to-noise ratio and shows some features of the stochastic resonance. As we have previously shown by using phospholipid species with different tendency to form non-lamellar structures, alamethicin channels are sensitive to the inherent stress of lipid packing with a membrane. We are able to relate quantitatively the channel conformational equilibrium seen in its opening and closing statistics to the membrane packing energetics. This is done through the study of statistical characteristics of alamethicin channels incorporated into a charged lipid membrane. In these experiments the charge per lipid molecule is changed by varying the pH of the membrane-bathing solution.