Interactions of Cu2+ ions with chicken prion tandem repeats

Abstract

The potentiometric and spectroscopic (EPR, UV-Vis, CD) data have shown that the chicken prion hexa-repeat (Ac–His–Asn–Pro–Gly–Tyr–Pro–NH₂) is a very specific ligand for Cu²⁺ ions. The His imidazole is an anchoring binding site, then the adjacent amide nitrogen coordinates as a second donor. The presence of Pro at position 3 induces binding of phenolate oxygen as a third donor atom. The tridentate coordination dominates around physiological pH. Similar to human octapeptide fragments, chicken tandem repeats exhibit a cooperative effect in binding Cu²⁺ ions, although chicken peptides are much less effective in metal ion coordination.