FIG. 7.

Fit of the single-channel conductance data of the cell wall channel PorA_Req as determined by multiplying the Renkin correction factor by the aqueous diffusion coefficients of the different cations. The product of the two numbers was normalized to 1 for a = 0.105 nm (Rb⁺). Single-channel conductances were normalized to the ones of Rb⁺ and plotted versus the hydrated ion radii taken from reference 50. The closed points correspond to Li⁺, Na⁺, K⁺, NH₄⁺, Cs⁺, N(CH₃)₄⁺, N(C₂H₅)₄⁺ and Tris⁺, which were all used for the pore-diameter estimation (see Discussion). The fit (solid lines) is shown for r = 1.4 nm (upper line) and r = 0.6 nm (lower line). The best fit was achieved with r = 0.9 nm (diameter = 1.8 nm), which corresponds to the broken line.