Broadband isolation of the antibody hexamer in complex with CD38 antigen molecules followed by collisional dissociation at acceleration voltages of (a) 100 V, (b) 150 V, and (c) 200 V. (d) Color annotation of fragment ions produced by collisional dissociation of the IgG1–005 hexamer:CD38 complex at 150 V colored according to the number of CD38 subunits present; the inset schematically shows suggested spatial arrangement of the subunits in the complex. As the dominant fragment ions series corresponds to an IgG:CD38 complex of 6:11, the predominant precursor ions should have been the 6:12 IgG:CD38 complex. Reproduced from Dyachenko, A., Wang, G., Belov, M., Makarov, A., de Jong, R.N., van den Bremer, E.T., Pareren, P.W.H.I., Heck, A.J.R. Anal. Chem., 2015, 87, 6095–6102 (ref 264). Copyright 2015 American Chemical Society.