The length ( L i ) and center ( Z i ) of the selected tile are (a) βγ-crystallin (pdb: 1h4a, X) L i = 43, Z i = 149.5; (b) myoglobin (pdb: 1mbd, A) L i = 18, Z i = 29; (c) green fluore... cent protein (pdb: 1gfl, A) L i = 15, Z i = 182.5; and (d) β-lactamase (pdb: 4blm, A) L i = 15, Z i = 185.5.