Figure 2.
Hydrolyzed β-lactam antibiotics bound to L1.Fo-Fc electron density maps (green mesh) calculated from the final refined structure after removal of ligand are shown contoured at 3σ (carbapenems and penam) or 2.8σ (cephalosporins). Hydrolyzed products (see Fig. S3 for chemical structures) are modeled for (A) doripenem (green), (B) tebipenem (cyan), (C) panipenem (purple), (D) mecillinam (orange), (E) cefoxitin (salmon), (F) cefmetazole (pink). Model bias was removed through the calculation of electron density maps after five rounds of refinement (in Phenix) of the structure in the absence of a ligand.