Abstract
We discuss the difference between osmotic permeability pf and diffusion permeability pd of single-file water channels and demonstrate that the pf/pd ratio corresponds to the number of effective steps a water molecule needs to take to permeate a channel. While pd can be directly obtained from equilibrium molecular dynamics simulations, pf can be best determined from simulations in which a chemical potential difference of water has been established on the two sides of the channel. In light of this, we suggest a method to induce in molecular dynamics simulations a hydrostatic pressure difference across the membrane, from which pf can be measured. Simulations using this method are performed on aquaporin-1 channels in a lipid bilayer, resulting in a calculated pf of 7.1 × 10-14 cm3/s, which is in close agreement with observation. Using a previously determined pd value, we conclude that pf/pd for aquaporin-1 measures ∼12. This number is explained in terms of channel architecture and conduction mechanism.
Original language | English (US) |
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Pages (from-to) | 50-57 |
Number of pages | 8 |
Journal | Biophysical journal |
Volume | 86 |
Issue number | 1 I |
DOIs | |
State | Published - Jan 2004 |
ASJC Scopus subject areas
- Biophysics