Figure 4.

The position of the regulatory points and the binding of Glu657 residue to Zn²⁺ ion on PBP-2′ protein folded structure. (a) On the folded structure the first penicillin binding site Ser25 (color cyan) and the metallic ligand binding site Glu657 (color black) are located on the surface while the second penicillin binding site Ser405 (color magenta) is not exposed on the surface but situated in an active site cavity. (b) This shows the Zn²⁺ ion (color grey) binding to the Glu657 residue (color blue) on the protein surface.