Figure 5.

Schematic view of model used to calculate the preferred location for lysine phenylalanine pairs. The excluded volume region represents the volume of benzene plus the volume unavailable to atoms of radius 1.7 Å. The cylinder is tangent to the benzene (radius = 4.8 Å), obtained by adding the radius of benzene (1.4 + 1.7 Å) and the radius of a neighboring carbon atom (1.7 Å). The shell is obtained by adding a constant radius of 2.8 Å—the diameter of a water molecule—to the excluded volume region. This view shows the only the top half of the excluded volume and has portions of the shell and cylinder removed for clarity.