FIGURE 15.

(A) CCS distributions for [M + 9H]⁹⁺-[M + 13H]¹³⁺ions of ubiquitin at various temperatures. Traces are shown in different colors when IMS peaks for different charge states show indistinguishable temperature profiles. (B) Relative abundance profiles as a function of temperature for each configuration reveal three distinct solution products (P₁, P₂, P₃) and one high-temperature equilibrium intermediate (I₂). Relative abundances of these identified conformers show distinct freezing curves as these conformers form from the unfolding/refolding of the compact, native ubiquitin ions at elevated temperatures. Reproduced from El-Baba et al. (2017). CCS, collision-induced unfolding.