FIGURE 6.

Crystal structures of caspase-3 in complexes with inhibitors. A, a ribbon diagram shows the overall structure of caspase-3. B, molecular surface maps represent the hydrophobic pocket with the bound inhibitors. C, a stereo view shows the composition of the hydrophobic pocket at the dimer interface and the oxidation of the catalytic cysteine (Cys¹⁶³) to sulfonic acid. D, the four inhibitors are superimposed at the binding site within bound compounds I, II, III, and IV colored in magenta, green, cyan, and yellow, respectively. E, a stereo view shows the catalytic active site of molecule C. The 2F_o - F_c sa_omit_map (1σ contour level) for the oxidized catalytic cysteine and the residues nearby are shown with cyan meshes.