PDKA inhibitor (4) with Asp633 superimposed with crystal structure of tetracyanobenzene (TCB) in complex with NaI (606750 entry at Cambridge Crystallographic Data Center as supplementary for small molecule anion-π complex structures (Berryman et al., 2007)) colored by element, TCB ring is slightly off-set for easier visualization. Halide shown as a purple sphere, TCB carbons are colored yellow; Asp633 with gray carbons represent Asp633 position in complex with single ortho-halogen substituted PDKAs (o-Br-PDKA shown), while Asp633 with black carbons represent Asp633 position for all other complexes (with PDKA, 1, 7 and 11). Atom colors: black, gray or yellow=carbon, red=oxygen, blue=nitrogen, white=hydrogen, purple=iodine. Images rendered in CHIMERA (Pettersen et al., 2004).