Metal–Peptide Complexes—A Novel Class of Molecular Receptors for Electrochemical Phosphate Sensing

Aleksandra Tobolska,Wojciech Bal,Wojciech Wróblewski,Urszula E Wawrzyniak,Nina E Wezynfeld

doi:10.3390/csac2021-10449

Abstract

Amyloid-β (Aβ) peptides are crucial in the pathology of Alzheimer’s disease. On the other hand, their metal complexes possess distinctive coordination properties that could be of great importance in the selective recognition of (bio)analytes, such as anions. Here, we report a novel group of molecular receptors for phosphate anions recognition: metal–peptide complexes of Aβ peptides, which combine features of synthetic inorganic ligands and naturally occurring binding proteins. The influence of the change in the metal ion center on the coordination and redox properties of binary Cu(II)/Ni(II)-Aβ complexes, as well as the affinity of these complexes towards phosphate species, were analyzed. This approach offers the possibility of fine-tuning the receptor affinity for desired applications.

Highlights

The determination of phosphate anions in body fluids provides information about various disorders such as hyperparathyroidism or vitamin D deficiency [1]
Metal–peptide complexes offer the possibility of fine-tuning their affinity for desired applications by altering the amino acid sequence and the metal ion center
The present work explores and compares the coordination and redox properties of Cu(II) and Ni(II) complexes of the Aβ5-9 peptide, followed by their ability to interact with biologically relevant phosphate anions and nucleotides

Summary

Introduction

The determination of phosphate anions in body fluids provides information about various disorders such as hyperparathyroidism or vitamin D deficiency [1]. Metal complexes, with their N-terminally truncated analogs, have unique coordination properties that could be employed in the design of potential receptors for biorelevant anionic species [3,4]. The Aβ5-9 (Arg-His-Asp-Ser-GlyNH2 ) peptide possesses a His-2 binding motif, and forms stable complexes with transition metal ions such as Cu(II) or Ni(II). At pH 7.4, the Cu(II) or Ni(II) ion is bound by three nitrogen atoms (3N) from the His residue, the N-terminal amine, and the peptide backbone amide [5]. Metal–peptide complexes offer the possibility of fine-tuning their affinity for desired applications by altering the amino acid sequence and the metal ion center. The present work explores and compares the coordination and redox properties of Cu(II) and Ni(II) complexes of the Aβ5-9 peptide, followed by their ability to interact with biologically relevant phosphate anions and nucleotides

Chemicals and Reagents

Peptide Synthesis

Voltammetry

Results and Discussion

Conclusions