Fig. 3.

IM-MS of “Aβ40 plus Porph” sample sets (Aβ40:Zn-Porph, 1:1) revealed the detection of new four signals. a 2D DriftScope IM-MS plots of the “Aβ40 plus Porph” sample at 20 μM. Peak apexes have been accentuated by dots denoting the new detected species. Numbers in parenthesis above peaks denote their experimental monoisotopic m/z with the positive charge state of the ions given as a superscript. The species with m/z at 1448.72, at 2173.63, and at 1735.08 are also labeled with identity tag assigned following the considerations described in the following paragraph. The species at 1448.72 and at 2173.63 were assigned to the protonated Aβ40 oxidized monomer, triply (Mox³⁺), and doubly (Mox²⁺) charged, respectively, while the species with m/z at 1735.08 was identified as the quintuply protonated dimer of Aβ40 consisting of one unit of oxidized Aβ40 and another of unmodified Aβ40 (Dox⁵⁺). b ESI-MS spectrum of an “Aβ40 plus Porph” sample at 5 μM. c ESI-MS spectrum of an “Aβ40 plus Porph” sample at 20 μM. Satellite peaks observed correspond to alkali metal adducts commonly observed in ESI-MS