Illustration of surface patches extracted from the crystal structure of asparagine synthetase (12AS). (a) The protein's atoms, color coded by solvent exposure from exposed (red) to buried (blue). A surface patch consists of all the exposed atoms within a sphere of radius r = 7Å (green) around a central surface β-carbon (pivot enlarged for illustration). (b) The surface of a single patch. (c) Neighboring patches on the protein surface typically overlap (the small magenta spheres represent pivots).