Mass spectrometry reflects key aspects of copper-amyloid β chemistry.

Mass spectrometry is a powerful method to study protein complexes; however, biochemical reactions are typically beyond the scope of MS studies. Here, we have studied the gas-phase redox chemistry of the [copper(II) - amyloid β] complex and show that the sequence-dependence of this chemistry reflects key aspects of the known behaviour of different variants of the peptide.

New Insights into the Intrinsic Electron-Based Dissociation Behavior of Cytochrome c Oligomers.

Between 2003 and 2017, four reports were published that demonstrated the intrinsic ability of the native iron-containing proteins cytochrome c and ferritin to undergo radical-based backbone fragmentation in the gas phase without the introduction of exogenous electrons. For cytochrome c in particular, this effect has so far only been reported to occur in the ion source, preventing the in-depth study of reactions occurring after gas-phase isolation of specific precursors. Here, we report the first observation of this intrinsic native electron capture dissociation behavior after quadrupole isolation of specific charge states of the cytochrome c dimer and trimer, providing direct experimental support for key aspects of the mechanism proposed 20 years ago.