Infrared Photoactivation Reduces Peptide Folding and Hydrogen-Atom Migration following ETD Tandem Mass Spectrometry

Electron capture dissociation (ECD)[1] results from the mutual storage of thermal electrons with multiply protonated peptide cations – an experiment generally performed within the high magnetic field of a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS). The technique is particularly useful as it generates random backbone cleavage with little regard to the presence of post-translational modifications (PTMs), amino acid composition, or peptide length. Electron transfer dissociation (ETD),[2] the ion-ion analogue of ECD, is conducted in radio frequency (RF) quadrupole ion trap devices where radical anions serve as electron donors. Because it can be implemented on virtually any mass spectrometer with an RF ion transfer or storage device, ETD has become an increasingly widespread dissociation method.