Figure 3.

Calculation of the electrostatic potential, φ(r) by solving the PB equation. In the PB equation ε(r) and κ²(r) are the position-dependent dielectric constant and ionic screening constant, respectively, and ρ(r) is the total atomic charge distribution in the system. κ(r) is 0 in zones II, III, and IV, and it is 1/9.8 A⁻¹ for zone I. Internally located residues E386 and E389 and externally positioned residues E322, D326, and E329 are represented as CPK space-filling mode. In solving the PB equation the bilayer was considered a continuum with a dielectric constant of two, the protein as a continuum with a dielectric constant of two and the solutions a continuum with a dielectric constant of 80.