PHYSICS OF IONIC CHANNELS AND OTHER PROTEINS WITH AQUEOUS CAVITIES

我们的研究利用了两种策略。 1)结构 离子通道的特征已经通过它们与 不同尺寸的聚合物。 2)电的快速动力学 传导已经通过复杂的物理“噪声”进行监测， 跟踪快速事件的分析，例如质子的结合和解结合 从电离位点;测试通道形成能力， 已知干扰细胞膜转运的抗生素; 测量大分子与驱动通道的能量之间的关系 在不同结构的功能状态之间。 根据α-毒素通道的动力学，可以测量α-毒素通道的浓度。 质子结合率和非结合在电离位点内 频道 丙甲霉素通道似乎在水溶性 聚乙二醇（PEGS）和葡聚糖。 添加的聚合物减少了 向更高电导状态过渡的概率，但不 改变频道寿命。 人们可以将每种聚合物的程度 排除到其回转半径和通道半径 毛孔 新生霉素是一种芳香族含氮抗生素，通常用作 药理学试剂以增强钠特异性， 阿米洛利敏感的神经纤维氯化钠，已被发现， 在脂质膜中形成离子通道。 通道可用作单个分子事件的快速检测器， 特别是质子与可电离位点结合。 的聚合物 可以使用不同的尺寸来测量通道尺寸。

Our studies have taken advantage of two strategies. 1) Structural features of ionic channels have been delineated by their reaction to polymers of varied size. 2) The very rapid kinetics of electrical conduction have been monitored through sophisticated physical "noise" analysis to follow rapid events such as binding and unbinding of protons from ionizable sites; to test for the channel-forming capabilities of antibiotics known to perturb cell membrane transport; to relate forces measured between macromolecules to the energies that drive channels between functioning states of different structures. From the kinetics of alpha-toxin channels, it was possible to measure the rate of proton binding and unbinding at ionizable sites within the channel. Alamethicin channels appear to speed up in the presence of water soluble polyethylene glycols (PEGS) and dextrans. Added polymers reduce the probabilities of transition to higher conductance states but do not change channel lifetimes. One can relate the degree of each polymer's exclusion to its radius of gyration and to the radius of the channel pore. Novobiocin, an aromatic nitrogen-containing antibiotic often used as a pharmacological agent to enhance the responses of sodium-specific, amiloride-sensitive nerve fibers to sodium chloride, has been found to form ion channels in lipid membranes. Channels can be used as rapid detectors of individual molecular events, in particular of proton binding to ionizable sites. Polymers of different sizes can be used to gauge channel dimensions.