_EC 6.6.1.- Forming coordination complexes. 16 PDB entries  
EC 6.-.-.- Ligases. [3,414 PDB entries]
EC 6.6.-.- Forming nitrogen-metal bonds. [16 PDB entries]
EC 6.6.1.- Forming coordination complexes. [16 PDB entries]
EC 6.6.1.1 magnesium chelatase. [13 PDB entries]
EC 6.6.1.2 cobaltochelatase. [3 PDB entries]