Overall structure of E. coli MetAP complexed with an inhibitor. Ribbon (A) and surface (B) drawings are shown for one of the structures with inhibitor 4 situated at the active site. The two Mn(II) ions are shown as green spheres, and the inhibitor is shown as sticks (yellow, carbon; red, oxygen; and blue, nitrogen). In ribbon drawing, the secondary structures are coded as red for α-helices, yellow for β-sheets, and green for loops and other structures. The YHGY loop (Y62, H63, G64 and Y65) is indicated by a red arrow.