Investigation of the Binding Properties of the Cosmetic Peptide Argireline and Its Derivatives Towards Copper(II) Ions

Isothermal titration calorimetry, potentiometric titration and circular dichroism spectroscopy were used to study the interaction of copper(II) ions with Argireline (Ac-Glu-Glu-Met-Gln-Arg-Arg-NH2) and three of its point mutation derivatives: Glu-Ala-Met-Gln-Arg-Arg-NH2 (AN1), Glu-Ala-His-Gln-Arg-Arg-NH2 (AN2) and Glu-Ala-Met-Gln-Ala-Arg-NH2 (AN3). Under the experimental conditions (20 mmol·L−1 Caco solution, pH 6, 298.15 K), copper(II) ions form 1:1 complexes with the peptides Argireline, AN1, and AN2. The complexation reactions are entropy-driven processes. The stability of the resulting complexes increases in the order log10KCu(AN1) < log10KCu(Argireline) < log10KCu(AN2). The relationship between the point mutations of Argireline and the binding properties of these peptides towards copper(II) ions is discussed.