Fig. 4

Visualization of the catalytic sites of CrmE10 (PDB: 7C23) and AlinE4 (PDB: 7C82). CrmE10 (a) and AlinE4 (b) are shown with electrostatic potential surfaces. Red: negative potential; blue: positive potential. The residues of the catalytic triad and oxyanion hole of CrmE10 (c) and AlinE4 (d) are shown as stick models. The Cd²⁺ ions in AlinE4 are shown as green spheres. The electronic density map is contoured to 1.0 σ at the 2Fo-Fc map. The dashed lines denoted hydrogen bonds. e The metal ion Cd²⁺ interacted with residues in the catalytic triad. The corresponding residues are indicated with a stick model. The electronic density map is contoured to 1.0 σ at the 2Fo-Fc map. The Cd²⁺ is shown as a green ball and the water molecule is shown as a red ball