A COMPUTATIONAL STUDY OF FACILITATED DIFFUSION USING THE BOUNDARY-ELEMENT METHOD

The steady-state equations of carrier-mediated transport are solved nu merically by means of the boundary element method and the limiting cas es of fast reaction, fast diffusion and excess of carrier are studied critically. It is confirmed that the facilitation factor, defined as t he ratio between the total flux of solute to that in the case of absen ce of carrier, shows a maximum for an optimal value of the equilibrium constant K of the solute-carrier reaction, Also, there appears to be a broad range of K values where neither the fast reaction assumption ( which is valid when the reaction proceeds much faster than the diffusi on) nor the fast diffusion assumption (valid in the opposite case) con stitute good approximations.