Electropumping of Water Through Human Aquaporin 4 by Circularly Polarized Electric Fields: Dramatic Enhancement and Control Revealed by Non-Equilibrium Molecular Dynamics.

An extensive suite of nonequilibrium molecular-dynamics (NEMD) simulations have been performed for ∼60 ns of human aquaporin 4 in externally applied circularly polarized (CP) electric fields, applied axially along channels. These external fields were 0.05 V/Å in intensity and 100 GHz in frequency. This has the effect of "electro-pumping" the water through the pores as prototypical biochannels, from conversion of molecules' spin angular momentum to linear momentum in the asymmetric heterogeneous-frictional environment of the pores, thus inducing overall net flow. Water's osmotic permeability was enhanced very substantially (doubled) vis-à-vis the zero-field case. This raises the tantalizing possibility of CP-field-mediated control of water permeability in aquaporins, or other biological (or biomimetic) channels as a potential viable and competitive water-treatment technology.