Anions nonsynergistic

Nonsynergistic anions, bound at secondary sites, have attracted attention because of their possible role in metal ion release (Section V.B). The ability of nonsynergistic anions to perturb the EPR spectra of transferrins was first shown by Price and Gibson (194), in a study of the known chaotropic ion C104 . This effect was subsequently exploited by Folajtar and Chasteen (195), using EPR difference spectra to study... 

Pig. 27. Possible sites for the binding of secondary, nonsynergistic anions, which may perturb the iron site and modulate release. Residue 121 is the essential arginine. Residues 210 and 301 are located behind the iron site, near the Tyr ligands and the hinge region. Numbering is as for the N-lobe of lactoferrin. The identities of these residues, which vary in the two lobes and between different transferrins, can be seen in Table III. 

---