FIGURE 8.

Three-dimensional view of a unit cell. One sixth of the unit cell is removed to show the interior. The surface of electron density distribution is chosen at a density value such that the central hole has a radius of 2.0 nm, according to the model. The low-resolution diffraction essentially reveals the layers of phosphate groups (top and bottom layers) and the layers of bromine atoms (two interior layers). An alamethicin channel of eight monomers arranged in the barrel-stave fashion fits the hole perfectly.