Table 1.

Summary of IMS-MS derived thermochemistry of model systems

System	Type of measurement	Insight about mechanism	Derived thermochemistry	Reference(s)
Pro peptides (Pro-13, Pro-7, HisPro-13)	Equil, kinetics	PPI↔PPII; trans→cis isomerization; configurationally coupled proton transfer	ΔG, ΔH, ΔS: multiple intermediates; ΔG‡, ΔH‡, ΔS‡ for TS	25, 64, 65
Peptides (bradykinin, Sub P)	Kinetics	Diketopiperazine formation; trans→cis isomerization; hidden intermediates	ΔG‡, ΔH‡, ΔS‡ for TS	12, 13, 33, 55
Single-domain proteins (CI-2, Ub)	Equil, LASER heating (μs)	Two-state transition involving multiple native and denatured conformations	Tm for many states; ΔG, ΔH, ΔS, ΔCp, energy landscapes (CI-2)	24, 27, 60
Multidomain protein complexes (Ub-dimer, Con A)	Equil	Complex dissociation; monomer subunits unfold independently (Ub); gradual structural change with increasing T (Con A)	Tm, ΔG, ΔH, ΔS, and ΔCp for many states	23
Protein–ligand, metal cofactors (myoglobin, myo-hemerythrin, hemoglobin)	Equil, LASER heating (μs)	Loss of α-helical structure; loss of heme and oxygen; presence of partially unfolded state at μs timescales; formation of non-native disulfide bond; dioxidation modification	Tm for multiple states and processes; tetramer states	76-78
Antibodies (IgG)	Kinetics	Light chain loss; non-native disulfide bond	ΔG‡, ΔH‡, ΔS‡ for loss of light chain	8
Escherichia coli lysate	Equil	Complex mixture; complexes dissociate	Tm for many unknown complexes	26
K-Ras and oncogenic mutants	Kinetics	Transition-state thermodynamics of the intrinsic GTPase activity	ΔG‡, ΔH‡, ΔS‡ for intrinsic GTPase activity	53
Membrane protein–lipid and protein–protein interactions (AmtB, AmtB–GlnK)	Equil	Binding thermodynamics for membrane protein–lipid and membrane protein–soluble protein interactions	ΔG, ΔH, ΔS, and ΔCp	14, 15

Abbreviations: CI-2, chemotrypsin inhibitor 2; IMS, ion mobility spectrometry; MS, mass spectrometry; TS, transition state.