If any of the atoms in the path were in a cycle, the cycle was added to the chelating group. 3 Same as A.1.3. The extraction process could lead to more than one metal-chelating group for a ligand in a PDB file. In these cases, the continuous group that had the largest number of atoms was kept. If for the same ligand in different PDB files different groups were obtained, all were kept. All extracted metal-chelating groups were saved as SMILES without stereochemistry and with hydrogen atoms added to the chelating atoms to mark that they were not substituted in the original ligand.