Single file water chain

Pomes, R. Roux, B., Molecular mechanism of H+ conduction in the single-file water chain of the gramicidin channel, Biophys. J. 2002, 82, 2304-2316... 

R. Pomes and B. Roux. Structure and dynamics of a proton wire A theoretical study of translocation along the single-file water chain in the gramicidin A channel. Biophys.]., 71 19-39,2002. 

In simulations of a wire of nine water molecules flanked by water droplets mimicking the influence of bulk water at either end of a membrane pore, proton migration was found to be activation-less throughout the single-file chain [Pomes and Roux, 1998], a result also suggested by a study of a tetrameric chain with droplets [Mei et al., 1998]. Thus, thermal fluctuations of proton wires in model hydrophobic channels are sufficient to drive the complete translocation within a few ps, despite the absence of an external field acting as driving force. 

Conduction of water through a CNT was found to occur in pulses. While the reason for such behavior is not fully understood, it can be attributed to the chain-like water arrangement inside a CNT. As the CNT wall is strongly hydrophobic, water molecules move smoothly without any hindrance from the wall, in a single file. 

Similar results were obtained from simulation of water molecules confined in narrow (6,6) carbon nanorings. Simulation also shows that at least two or more water chains should be present inside the nanotube or nanoring to exhibit single-file diffusion [7,8]. 

E. Fois et al.. Water molecules in single file first-principles studies of one-dimensional water chains in zeolites. J. Phys. Chem. B 105(15), 3012-3016 (2001)... 

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