Dual functions of β-amyloid oligomer and fibril in Cu(II)-induced H2O2 production

Amyloid-β (Aβ) aggregation and Cu(II)-related oxidative stress are involved in the dysfunction and death of neurons in Alzheimer's disease (AD). However, the relationship between Aβ and Cu(II) is not clear. Furthermore, the pro- or anti-oxidant properties of Aβ are also under great debate. Here the H2O2 generating ability of Aβ42 in its monomeric, oligomeric and fibrillar forms was studied in the presence of Cu(II). The results show that Aβ42 in both oligomeric and fibrillar forms can promote H2O2 generation at lower concentrations of Cu(II) and Aβ42 oligomer can promote H2O2 generation to a higher extent. Nevertheless, the promoting effect of Aβ42 oligomer and fibril may convert to an inhibitory effect when the concentration of Cu(II) is increased. This indicates the dual functions of Aβ42 oligomer and fibril in Cu(II)-induced H2O2 production. Hereby we present a new perspective on the roles of Aβ42 in Cu(II)-mediated oxidative stress and add new evidence to the viewpoint that Aβ42 oligomer may be primarily responsible for the pathogenesis of AD.