Table 2.

Ligand biochemistry

C-Ring in ligand	C or N atoms in ligand recognizing by connection information in the PDB
Unprotonated atoms in ligand	1) O has a connection with N, P or Zn
	2) O only has a connection with C
Protonated atoms in ligand	1) Ca
	2) N has only two connection with C

The bond list is given in the PDB file CONECT lines.