The Cu(II) affinity constant and reactivity of Hepcidin-25, the main iron regulator in human blood

Dawid Płonka; Marta D Wiśniewska; Joanna Ziemska-Legięcka; Marcin Grynberg; Wojciech Bal

doi:10.1016/j.jinorgbio.2023.112364

The Cu(II) affinity constant and reactivity of Hepcidin-25, the main iron regulator in human blood

J Inorg Biochem. 2023 Nov:248:112364. doi: 10.1016/j.jinorgbio.2023.112364. Epub 2023 Sep 2.

Authors

Dawid Płonka¹, Marta D Wiśniewska¹, Joanna Ziemska-Legięcka¹, Marcin Grynberg¹, Wojciech Bal²

Affiliations

¹ Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, Warsaw 02-106, Poland.
² Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, Warsaw 02-106, Poland. Electronic address: wbal@ibb.waw.pl.

PMID: 37689037
DOI: 10.1016/j.jinorgbio.2023.112364

Abstract

Hepcidin is an iron regulatory hormone that does not bind iron directly. Instead, its mature 25-peptide form (H25) contains a binding site for other metals, the so-called ATCUN/NTS (amino-terminal Cu/Ni binding site). The Cu(II)-hepcidin complex was previously studied, but due to poor solubility and difficult handling of the peptide the definitive account on the binding equilibrium was not obtained reliably. In this study we performed a series of fluorescence competition experiments between H25 and its model peptides containing the same ATCUN/NTS site and determined the Cu(II) conditional binding constant of the CuH25 complex at pH 7.4, ^CK_7.4 = 4 ± 2 × 10¹⁴ M^-1. This complex was found to be very inert in exchange reactions and poorly reactive in the ascorbate consumption test. The consequences of these findings for the putative role of Cu(II) interactions with H25 are discussed.

Keywords: ATCUN; Binding constant; Copper complex; Hepcidin; Kinetics; Redox.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Binding Sites
Fluorescence
Hepcidins*
Humans
Iron*
Protein Domains

Substances

Iron
Hepcidins