Figure 4. Active site pockets of the PA endonuclease.

Each panel shows the pH1N1 domain in surface representation (green) in the same orientation with the manganese ions as pink spheres. Bound compounds are shown in surface and stick representation. Some residues underlying prominent surface features are indicated in white. A. Native unliganded structure. B. R05-3A (brick). C. EGCG (grey). D. R05-2 (yellow). In the native state, the active site cavity is large. The different compounds fill various sub-pockets of the cavity (indicated in red) and induced fit movements tend to close up the active site, but the cavity is never entirely filled.