FIGURE 6.

(a) Close-up view of the extracellular side of AqpZ showing the Asn¹⁸² mutation site. Green sticks and surface dots represent the side chain and the molecular surface of Asn¹⁸², respectively. Mutation of this residue to glycine removes the side chain. (b) Channel radius r_c, wild-type (red), L170V (green), N182G (blue), and L170V/N182G (cyan), calculated by the average of the eight monomers in the two independent 5-ns simulations. The NPA motifs and ar/R region are indicated in semitransparent yellow and cyan, respectively. The horizontal axis represents the z-axis. (c) Number density of channel waters. (d) The order parameter P₁(z) = 〈cosθ〉, where θ is the angle between the dipole moment of water and the z-axis.