Condition-Dependent Coordination and Peroxidase Activity of Hemin-Aβ Complexes

The peroxidase activity of hemin-peptide complexes remains a potential factor in oxidative damage relevant to neurodegeneration. Here, we present the effect of temperature, ionic strength, and pH relevant to pathophysiological conditions on the dynamic equilibrium between high-spin and low-spin hemin-Aβ(40) constructs. This influence on peroxidase activity was also demonstrated using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and dopamine (DA) oxidation rate analyses with increasing ratios of Aβ(16) and Aβ(40) (up to 100 equivalents). Interaction and reactivity studies of aggregated Aβ(40)-hemin revealed enhanced peroxidase activity versus hemin alone. Comparison of the results obtained using Aβ(16) and Aβ(40) amyloid beta peptides revealed marked differences and provide insight into the potential effects of hemin-Aβ on neurological disease progression.