Figure 1.

(a) Formation of [Aβ + Fe³⁺ + H]⁴⁺ after IR activation of the ternary complex between amyloid β and [Fe-NTA]. Inset shows the observed and calculated isotope distribution of the product ion, confirming the 3+ oxidation state of Fe. Longer exposure to the IR laser induced backbone fragmentation, as shown in (b). The observed b/y fragment ions both with and without bound Fe³⁺ are summarized below the fragment spectrum, and the apparent binding region is indicated with a yellow highlight. Fragment charge states are indicated using a color code