1/f fluctuation and water permeation of aquaporins

Aquaporins (AQPs) are transmembrane water channels that exclusively transport water molecules across the plasma membranes. Using all-atom molecular dynamics simulations for a system of AQP1/water molecules/lipid bilayer, we investigated the effects of conformational fluctuations of amino acids on water pemeation within AQP1. We found that the amino acids exhibit 1/f fluctuations, indicating possession of long-term memory. In this case, water molecules crossing the ar/R region obey a non-Poisson process. Moreover, we performed restrained MD simulations of AQP1. In restrained MD simulations, the fluctuations of amino acids show white Gaussian fluctuation, and water molecules crossing the ar/R region obey a Poisson process. These results suggest that 1/f fluctuations of amino acids generate the non-Poisson water permeation within AQP1.