Figure 1.

The figure on the left side represents the X-ray of CES1 complexed with naloxone (PDBID: 1mx9). The figure on the right side is a zoom on the binding site of CES1 where naloxone is located. The protein is represented as a grey transparent surface. Residue side chains within 4.5 Å of the ligand are shown as green sticks. Hydrophobic interactions are predominant. Intermolecular hydrogen bonds are shown as cyan dashes. The catalytic triad residues Ser221–Glu354–His468 located at the base of the active gorge and between the rigid and flexible pockets are shown in thick sticks. The average distance between Ser221 side chain and naloxone’s hydroxyl group is indicated with a solid red line.