A Deeper Insight in Metal Binding to the hCtr1 N-terminus Fragment: Affinity, Speciation and Binding Mode of Binuclear Cu2+ and Mononuclear Ag+ Complex Species

International Journal of Molecular Sciences

Giuseppe Arena¹  Antonio Magrì²  Enrico Rizzarelli²  Giovanni Tabbì²  Irina Naletova²  Francesco Attanasio² 

[1] Department of Chemical Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy;Institute of Crystallography, National Council of Research, CNR, S.S. Catania, Via P. Gaifami 18, 95126 Catania, Italy;

关键词: Ctr1;    model transporter;    copper;    silver;    speciation;    affinity;   

DOI  :  10.3390/ijms23062929

来源: DOAJ

【 摘 要 】

Ctr1 regulates copper uptake and its intracellular distribution. The first 14 amino acid sequence of the Ctr1 ectodomain Ctr1_(1-14) encompasses the characteristic Amino Terminal Cu²⁺ and Ni²⁺ binding motif (ATCUN) as well as the bis-His binding motif (His5 and His6). We report a combined thermodynamic and spectroscopic (UV-vis, CD, EPR) study dealing with the formation of Cu²⁺ homobinuclear complexes with Ctr1_(1-14), the percentage of which is not negligible even in the presence of a small Cu²⁺ excess and clearly prevails at a M/L ratio of 1.9. Ascorbate fails to reduce Cu²⁺ when bound to the ATCUN motif, while it reduces Cu²⁺ when bound to the His5-His6 motif involved in the formation of binuclear species. The histidine diade characterizes the second binding site and is thought to be responsible for ascorbate oxidation. Binding constants and speciation of Ag⁺ complexes with Ctr1_(1-14), which are assumed to mimic Cu⁺ interaction with N-terminus of Ctr1_(1-14), were also determined. A preliminary immunoblot assay evidences that the anti-Ctr1 extracellular antibody recognizes Ctr1_(1-14) in a different way from the longer Ctr1_(1-25) that encompasses a second His and Met rich domain.

【 授权许可】

Unknown