Figure 3. Spherical coordinates of arginine with (A,B) aspartate and glutamate and (C,D) asparagine and glutamine.
(A,C) Two spherical coordinate parameters (ψ and θ) are plotted for oxygens interacting with arginine, showing three distinct interaction geometries. Examples of the interactions are shown in (A): backside (left), end on (middle), and side on (right). (B,D) The spherical coordinate parameters (ψ and ρ) show the relationship of distance to in-plane angle. Data points are colored by density, with red being the most dense.