Polder omit map of the Y363F HDAC6 CD1–AR-42 complex (PDB 6UO5; contoured at 6.0 σ; F363 is contoured at 3.0 σ). Atoms are color-coded as follows: C = light blue (monomer A), light gray (symmetry mate), or wheat (inhibitor), N = blue, O = red, Zn2+ = gray sphere, and water molecules = smaller red spheres. Metal coordination and hydrogen bond interactions are indicated by solid and dashed black lines, respectively.