Table 1.

Examples of experimental approaches for characterising conformational ensembles populated on the protein energy landscape

Experiment	Technique	Species
Kinetic
Folding/assembly	Spectroscopy (absorption, fluorescence, infra-red, circular dichroism etc.)	U, I, N, O, A
	NMR (real time, relaxation and line-shape analysis etc.)	U, I, N
	Mass spectrometry	U, I, N, O, A
	Single molecule experiments (FRET, FCS etc.)	U, I, N, A
	Protein engineering (phi-value analysis∗ etc.)	U, I, N
	Specific dye binding (ANS, Thioflavin T etc.)	U, I, N, O, A
	Hydrogen–deuterium exchange∗	U, I, N, O, A
	Turbidity and light-scattering	N, O, A
	Chemical cross-linking	O, A
Equilibrium
Structure	X-ray crystallography	N
	Fibre diffraction	A
	Electron paramagnetic resonance (EPR)	A
	Solution NMR (NMR order parameters∗, residual dipolar couplings∗, nuclear Overhauser effects∗ etc.)	U, I, N
	Solid state NMR	O, A
	Cryo-electron microscopy	A
Conformation	Spectroscopy (see above)	U, I, N, O, A
	Electron and atomic force microscopy (EM and AFM)	O, A
	Analytical ultracentrifugation	U, I, N, O
	Gel permeation chromatography	U, I, N, O
	Calorimetry	U, I, N
Dynamics	NMR (relaxation measurements∗, residual dipolar couplings∗, spin-labelling techniques∗ etc.)	U, I, N
	Hydrogen–deuterium exchange∗	U, I, N, O, A
	Denaturant and proteolysis stability	U, I, N, O, A

The observable states are grouped into native state (N), intermediate state (I), unfolded state (U), oligomeric states (O) and amyloid fibrils (A). Experimental data from techniques marked by an asterisk might be used as restraints in molecular dynamics simulations. Adapted from [9].