Fig. 3

A new and unique substrate-binding pocket (Site II) of AgPPO8. (a) AgPPO8 contains a cavity approximate to surface (Site II, side view). The cavity and solvent exposed surface areas are represented in cyan and gray, respectively. The key residues surrounding the cavity are shown as violet sticks. (b) The side view of Site II pocket with tyramine (green) and dopamine (yellow) docked inside. The distances (Å) from the phenolic oxygens of the substrates to CuA and CuB are indicated. (c and d) Superposition of the active sites before and after docking. The active site residues of the apo-AgPPO8 are shown as magenta sticks, while the complex structures with docked substrates bound are colored in cyan (tyramine) and green (dopamine), respectively. The hydrogen bonding between the substrate and E364 is highlighted with black dash. The distances (Å) from E364 to CuA, CuB, the putative placeholder F99, and the phenolic oxygens of docked substrates (yellow sticks) are indicated. The distance of the salt bridge between residues E364 and R244 is also labeled (before docking, magenta; after docking, tyramine, cyan and dopamine, green). CuA and CuB are shown as brown spheres