Substrate-binding pocket and interactions of BuPAG 7 with pepstatin.

(A) The overall structure of BuPAG 7 in complex with pepstatin in its substrate-binding pocket. Pepstatin is shown in ball and sticks representation (cyan) and interacting residues in sticks representation (green). (B) Residues involved in hydrogen bonding and other interactions with the side chains of pepstatin in sticks representation (cyan). (C) A schematic representation of interactions of pepstatin with BuPAG 7 generated using ligplot. Interactions involve both hydrogen bonding and hydrophobic contacts. Hydrogen bonds are indicated by dashed lines (green) between the atoms involved, while hydrophobic contacts are represented by an arc (red) with spokes radiating towards the ligand atoms they contact. The contacted atoms are shown with spokes radiating back.