The N-terminus of hepcidin is a strong and potentially biologically relevant Cu(II) chelator.

Abstract

Hepcidin is an iron regulatory hormone, involved also in immune response in vertebrates. It contains the N-terminal Asp-Thr-His site able to bind Cu(II) ions. A significant discrepancy exist in the literature regarding Cu(II) affinity of this site in hepcidin. Our study focused on the model DTHFPI-NH2 hexapeptide reflecting the N-terminal motif of mature hepcidin Using potentiometry, UV-vis and CD spectroscopies we demonstrated that DTHFPI-NH2 is the strongest Cu(II) binding peptide discovered so far. A competition assay with human serum albumin (HSA) confirmed this high affinity and demonstrated that DTHFPI-NH2. withdraws all Cu(II) from HSA under equimolar concentrations. Based on these results we propose that hepcidin could exist as Cu(II) complex in blood, especially under inflammatory conditions, when its serum concentration is elevated.