... (Table 1). The bind-ing of the ®rst CN±ligand to the iron was thus more easy in the hydrophobic binding pocket of the antibody than the binding of the second one, most probably because of the steric ... distortion of the porphyrin ring anda shift of the iron atom outside the plane of the porphyrin.Binding of imidazole to the iron(III) of Fe(ToCPP),a,a-1,2- a,b-1,2-Fe(DoCPP), Fe(MoCPP)and to their ... shown). This showsthat the binding of the two cyanide ligands to the ironatom of 13G10±Fe(ToCPP) actually occurred inside the binding pocket of the antibody. The value of the dissoci-ation constant...