Single file water transport across peptidic nanopores

孔隙几何形状将水限制在与孔隙相互作用的一维分子文件中，改变了水的物理特性。流动动力学的变化部分是由于与本体流体相比氢键数量的减少。预测周转率从通道的几何形状（长度和直径），并从散装水的扩散系数，宏观模型显然无法描述率的单行水运输，膜通道之间的几个数量级的差异。例如，去甲肾上腺素使短杆菌肽-A的水渗透性增加超过扩散极限。我们现在的目标是研究毛细管蒸发和纳米孔中的冰状结构，这是预测发生的分子动力学模拟。插入平面双层后，水流过各种新的短杆菌肽衍生物将通过扫描微电极测量。通过分子动力学模拟计算纳米孔几何形状和疏水性对水和质子渗透速率的影响，以深入了解单列水传输的分子机制。这将允许设计和合成具有优化的渗透特性的新型纳米孔。由于水的有序化可以通过“质子线”氢键网络调节质子电导，因此可能的应用包括可切换的纳米级导体。

Confinement of water by pore geometry to a one-dimensional file of molecules interacting with the pore alters its physical characteristics. Changes in flow dynamics is partially due to the reduction in number of hydrogen bonds compared to the bulk fluid. Predicting the turnover rate from channel geometry (length and diameter) and from the diffusion coefficient in bulk water, macroscopic models clearly fail to describe the rates of single file water transport, which differ by several orders of magnitude among membrane channels. Desformylation, for example, increases the water permeability of gramicidin-A beyond the diffusion limit. We now aim to investigate both capillary evaporation and icelike structures in nanopores, which are predicted to occur by molecular dynamics simulations. After insertion into planar bilayers, water flow across a variety of new gramicidin derivatives will be measured by scanning microelectrodes. The effect of nanopore geometry and hydrophobicity on water and proton permeation rates is calculated by molecular dynamics simulations to gain insight into the molecular mechanism of single file water transport. This will allow design and synthesis of novel nanopores with optimized permeation characteristics. Since water ordering may modulate proton conductance via a "proton wire" hydrogen-bonding network, possible applications include switchable nanoscale conductors.