| 초록 |
It is well known that aquaporins in the cell membranes such as AQP1 are highly selective for the water and prevent protons and ions from crossing the membrane. The recent studies based on X-ray crystallography have suggested that the proton-exclusion in aquaporin is due to the breakage of hydrogen bonding network. As for the ion-exclusion process, however, its mechanisms in connection with such selective transport of water molecules are still unrevealed. In the present work, water-permeation in an AQP1 channel is simulated by an atomistic molecular dynamics simulation in order to elucidate the ion-exclusion mechanisms in the water permeation process. The free energy profiles of water molecules and ions passing through the AQP1 channel are obtained by calculating the potential mean force (PMF). It is found that the free energy barriers for the permeation of ions are much higher than that for the water permeation, which is mainly attributed to dehydration of ions and the breakage of hydrogen bonding between neighboring water molecules by the central motif and two pore helices. |
