Collision-Induced Unfolding Studies of Proteins and Protein Complexes using Drift Tube Ion Mobility-Mass Spectrometer.

Elucidating the structures and stabilities of proteins and their complexes is paramount to understanding their biological functions in cellular processes. Native mass spectrometry (MS) coupled with ion mobility spectrometry (IMS) is emerging as an important biophysical technique owing to its high sensitivity, rapid analysis time, and ability to interrogate sample complexity or heterogeneity and the ability to probe protein structure dynamics. Here, a commercial IMS-MS platform has been modified for static native ESI emitters and an extended mass-to-charge range (20 kDa m/z) and its performance capabilities and limits were explored for a range of protein and protein complexes. The results show new potential for this instrument platform for studies of large protein and protein complexes and provides a roadmap for extending the performance metrics for studies of even larger, more complex systems, namely, membrane protein complexes and their interactions with ligands.