Conformational landscapes of rigid and flexible molecules explored with variable temperature ion mobility-mass spectrometry

Understanding the effect of temperature to the structural integrity of proteins is relevant to diverse areas such as biotechnology and climate change. Variable temperature ion mobility-mass spectrometry (VT-IM-MS) can measure the effect of temperature on conformational landscapes. To delineate collision effects from structural change we report measurements using molecules with different degrees of rigidity namely: poly (L-lysine) (PLL) dendrimer, ubiquitin, β-casein and α-synuclein from 190-350 K. The CCS of PLL dendrimer varies with temperature consistent with collision theory, by contrast, the structure of each protein alters with notable restructuring at 350 K and 250 K, following predicted in vitro stability curves. At 210 K and 190 K we kinetically trap unfolding intermediates. For alpha-synuclein, the 13+ ions present two distinct conformers and VT-IM-MS measurements allow us to calculate the transition rate and activation energies of their conversion. These data exemplify the capacity of VT-IM-MS to provide insights on the thermodynamics of conformational restructuring.