The interactions of glycated decapeptide, the Amadori product, with copper(II) ions – A possible effect on the oxidative stress induced aggregation?

The coordination of Cu2+ ions by two linear decapeptides: H-Asp-Asp-Ser-Pro-Asp-Leu-Pro-Lys-Leu-Lys-OH (P1) and H-Asp-Asp-Ser-Pro-Asp-Leu-Pro-Lys(Fru)-Leu-Lys-OH (P2) was studied in detail and complex formation in 3–11 pH range was described. Their Cu2+ binding properties were investigated in depth through a variety of physicochemical methods including potentiometry and spectroscopic analysis (UV–Vis, EPR, CD and ESI-MS). Moreover, quantum chemical calculations were performed to explain experimental parameters. Obtained results suggest differences in the Cu2+ complex formation between analyzed ligands. For glycated analog (P2) the presence of bis-complex CuHL2 is detected, which was confirmed by MS spectrometry. Moreover, the comparison of binding efficiency of two peptides indicated that coordination of metal ion by peptide (P2) in the physiological pH range is significantly stronger than non-glycated analog (P1).