Closeness centrality is mapped to structure for: (a) P. purpurogenum Acetylxylan esterase (1BS9), (b) e. coli Endonuclease III (2ABK) and (c) C. papaya papain (9PAP). In all three cases, the most central residues occur near the center of the structure, which do not correspond to the catalytic residues. In each column, red indicates the most central residues; whereas blue indicates the least. In the column on the left, catalytic residues are shown in spacefill. In the center column, all atoms are displayed; in the column on the right, the structure has been sliced in half to highlight the most central residues within the hydrophobic core.