Figure 5.

Active site of AprA showing the environment of the conserved methionine (M214). A: The three histidine ligands (labelled) are shown along with the zinc ion (in green). The spacefill representation (B) shows the closely packed arrangement around the methionine residue, as well as its proximity to the catalytic zinc and the three histidine residues. Protons (white) were added to the M214 methyl group for clarity. Based on structure from PDB entry 1KAP [15].