A new theory of transport for cell membrane pores. II. Exact results and computer simulation (molecular dynamics)

An exact expression for the solvent diffusion coefficient in a pore that is so narrow that two molecules cannot get around each other is derived. The theory states that the diffusion coefficient for a pore that contains n molecules is simply equal to the diffusion coefficient a molecule would have if it were all alone in the pore (D°) divided by n. The theory is very general. Two different models that can be used to determine D° are described. An exact experimental test of the theory is carried out by the use of computer simulation (molecular dynamics). It is shown that as long as the density of molecules in the pore is not too high, the experimental results are not significantly different from the theoretical preditions. These experimental results also test the theory presented in the first paper of this series and provide strong support for those results.