Dynamics of Intact Immunoglobulin G Explored by Drift‐Tube Ion‐Mobility Mass Spectrometry and Molecular Modeling

Collision cross-sections (CCS) of immunoglobulins G1 and G4 have been determined using linear drift-tube ion-mobility mass spectrometry. Intact antibodies and Fc-hinge fragments present with a larger range of CCS than proteins of comparable size. This is rationalized with MD simulations, which indicate significant in vacuo dynamics between linked folded domains. The IgG4 subclass presents over a wider CCS range than the IgG1 subclass.