Monoclonal antibodies (mAbs) are important therapeutic glycoproteins, but their large size and structural complexity make them difficult to rapidly characterize. In a recent publication, Jean Lodge et al. present the first application of Activated ion electron transfer dissociation (AI-ETD) to mAb sequencing. For the standard NIST mAb, they found a high degree of complementarity between fragments generated using standard ETD with a short reaction time and AI-ETD with a long reaction time. Most importantly, AI-ETD revealed disulfide-bound regions that have been intractable, thus far, for sequencing with top-down MS.