Redox Kinetics of the Amyloid-β-Cu Complex and Its Biological Implications.

The ability of the amyloid-β peptide to bind to redox active metals and act as a source of radical damage in Alzheimer's disease has been largely accepted as contributing to the disease's pathogenesis. However, a kinetic understanding of the molecular mechanism, which underpins this radical generation, has yet to be reported. Here we use a sensitive fluorescence approach, which reports on the oxidation state of the metal bound to the amyloid-β peptide and can therefore shed light on the redox kinetics. We confirm that the redox goes via a low populated, reactive intermediate and that the reaction proceeds via the Component I coordination environment rather than Component II. We also show that while the reduction step readily occurs (on the 10 ms time scale) it is the oxidation step that is rate-limiting for redox cycling.