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

The comparison of the efficiency of the metal ion binding clearly indicates that Cu2+ ions are coordinated more effective by glycated ligand (P2). It can be assigned to the third nitrogen donor binding, where formation of 3N complex take place in a more acidic pH range with lower pK value about 1.11 units. Moreover, for glycated analog (P2) the formation of bis-complex is proposed, as it was proved by ESI-MS spectrometry and potentiometric calculations. Thus, probably the impact of glycation at the lysyl residue may have some influence on the peptide chain rearrangement and 3N complex formation, which exists in a two forms: CuH−1L and CuHL2. Furthermore, in literature, some information of high pK values of free sugar deprotonation and binding abilities of glucose and related sugar analogs towards Cu2+ are proposed. Thus, it may suggest the involvement of sugar residue in the coordination of Cu2+.