Electron capture-induced dissociation of AK dipeptide dications: Influence of ion velocity, crown-ether complexation and collision gas

The fragmentation of doubly protonated AK dipeptide ions has been investigated after collisional electron transfer. Electron capture leads to three dominant channels, H loss, NH3 loss, and N-Cα bond breakage to give either c+ or z+ fragment ions. The relative importance of these channels has been explored as a function of ion velocity, the degree of complexation with crown ether, and collision gas. Our results indicate that H loss and NH3 loss are competing channels whereas the probability of N-Cα bond breakage is more or less constant.