|Custom fragment ion for ECD
I was trying to look for a custom fragment ion from ECD and ETDhcd spectra for the isoAspartate residue of the peptide that gives off either c+57 or z-57 ions. I am able to add c and z ions in transition settings but unable to add any other loss/ gain to it. One workaround I had to this problem was to use a peptide modification of 57 gain/ loss and then select the c ions with a 57 loss or z ions with 57 gain. So is there any other simpler way to do this custom fragment ion search?