The Cu²⁺ complex of this soluble amyloid β-protein fragment showed significant oxidative activities toward the catechol-like substrate 1,2,3-trihydroxylbenzene (pyrogallol) and plasmid DNA cleavage. The N-terminal Aβ fragments Aβ1-14, Aβ1-15, and Aβ1-16 are elevated in cell media and in CSF in response to γ-secretase inhibitor treatment. The fragments can serve as biomarkers in clinical studies of the effect of such inhibitors. Proteins interactions with reactive oxygen agents may result in covalent modifications of amino acid residues in proteins, formation of protein-protein cross-linkages and oxidation of the protein backbone resulting in protein fragmentation. Oxidation targets for Aß(1-16) are the histidine residues coordinated to the metal ions. Copper is bound to Aß in senile plaque of Alzheimer’s disease with Aß (1-16) taking part in the coordination of the Cu2+ ions. Cu2+ and Zn2+ are linked with the neurotoxicity of Aß and free radical damage.