title: Molecular dynamics studies on the influences of a gradient electric field on the water chain in a peptide nanotube.
abstract: The structure and transportation characteristics of the water chain inside a 8×cyclo-(WL)4 peptide nanotube (PNT) were simulated under a gradient electric (GE) field. The gradient was defined by the ratio of a constant (Ea) and the z-directional length (Lz) of the simulation box. Ea varies from 0.0 to 0.9 V nm(-1). As the gradient increases, the probabilities of finding two water molecules in an α-plane zone and three in a midplane region increase. To accommodate more water molecules, the axial array of channel water molecules becomes more compact. Meanwhile, the H-bonded network between the channel water is greatly intensified when Ea increases from 0.3 to 0.9 V nm(-1). Nevertheless, the proportion of strong H-bonds does not increase significantly following the formation of a more compact axial array of water molecules. When Ea reaches 0.9 V nm(-1), the water molecule in an α-plane zone may be dragged by its neighboring water molecules into the midplane region, resulting in a significant deviation from the channel axis. With the augment of the gradient, the dipoles of channel water are gradually oriented along the tube axis in the sequence from gap 1 to 7, namely along the direction of the electric field. Nevertheless, even when E a reaches 0.9 V nm(-1), the dipole orientation of the channel water is not complete, and dipole flips still occur in gap 7. Under a GE field, the rightward and leftward hopping rates of channel water are no longer equal to each other, i.e., channel water performs an asymmetric transportation.
authors: College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, China.
authors: Hui
authors: H
authors: Li
authors: Jianfen F
authors: JF
authors: Fan
authors: Rui
authors: R
authors: Li
authors: Yi
authors: Y
authors: Yu
authors: Xiliang L
authors: XL
authors: Yan
mesh_terms: D004560:Electricity; D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D045333:Nanotubes, Peptide / Q000737:chemistry*; D011312:Pressure; D011336:Probability; D055672:Static Electricity; D014867:Water / Q000737:chemistry*
chemical_list: D045333:Nanotubes, Peptide; D014867:Water