H-ASP-ALA-GLU-PHE-ARG-HIS-ASP-SER-GLY-TYR-GLU-VAL-HIS-HIS-GLN-LYS-OH

β-amyloid (1-16) fragment is considered as valid models to examine the contribution of the key histidine residues (His , His in mouse and His , His , His in human fragments) to the Ab–Cu²⁺ interaction. Oxidation targets for β-Amyloid (1-16) are the histidine residues coordinated to the metal ions. Copper is bound to Aβ in senile plaque of Alzheimer’s disease with β-Amyloid (1-16) taking part in the coordination of the Cu²⁺ ions. Cu²⁺ and Zn²⁺ are linked with the neurotoxicity of -Amyloid and free radical damage^[1]. β-amyloid (1-16) is the minimal amino acidic sequence display a Cu coordination mode which involves three Histidines (His6, His13 and His14). β-amyloid (1-16) is supposed to be involved in metal binding^[2]. Human β-amyloid interacts with zinc ions through its metal-binding domain 1-16. The C-tails of the two polypeptide chains of the rat Aβ(1-16) dimer are oriented in opposite directions to each other, which hinders the assembly of rat Aβ dimers into oligomeric aggregates. Thus, the differences in the structure of zinc-binding sites of human and rat β-Amyloid (1-16), their ability to form regular cross-monomer bonds, and the orientation of their hydrophobic C-tails could be responsible for the resistance of rats to Alzheimer's disease^[3].