Figure 2.

Polder omit maps (green mesh) contoured at 3.0 sigma for compounds (a) 1 (orange), (b) 2 (orange/purple), (c) 3 (yellow), and (d) Bavarostat (blue) complexed with HDAC6 (white). The catalytic Zn2+ ion appears as a grey sphere; metal coordination and hydrogen bond interactions are shown as solid and dashed black lines, respectively. Atoms from a symmetry-related molecule in the crystal lattice are shown with dark grey carbon atoms. In (b), the monodentate hydroxamate conformation of 2 is shown in orange and the bidentate conformation is shown in purple. The binding of 1 (a) and 3 (c) illustrates exclusive monodentate hydroxamate-Zn2+ coordination; the binding of 4 (Bavarostat) (d) illustrates exclusive bidentate hydroxamate-Zn2+ coordination.