_EC 6.3.3.- Cyclo-ligases. 138 PDB entries  
EC 6.-.-.- Ligases. [3,414 PDB entries]
EC 6.3.-.- Forming carbon-nitrogen bonds. [1,455 PDB entries]
EC 6.3.3.- Cyclo-ligases. [138 PDB entries]
EC 6.3.3.1 phosphoribosylformylglycinamidine cyclo-ligase. [61 PDB entries]
EC 6.3.3.2 5-formyltetrahydrofolate cyclo-ligase. [10 PDB entries]
EC 6.3.3.3 dethiobiotin synthase. [59 PDB entries]
EC 6.3.3.4 (carboxyethyl)arginine beta-lactam-synthase. [5 PDB entries]
EC 6.3.3.5 O-ureido-D-serine cyclo-ligase. [1 PDB entries]
EC 6.3.3.6 carbapenam-3-carboxylate synthase. [2 PDB entries]
EC 6.3.3.7 Ni-sirohydrochlorin a,c-diamide reductive cyclase. [-]

[-] signifies that there are no PDB entries for the given enzyme subclass