Despite significant experimental advances in NMR spectroscopy that have brought forth the characterization of a diverse range of unfolded proteins, conformational exchange and dynamic averaging have generally hampered detailed analysis of such structural ensembles.Using photochemically induced dynamic nuclear polarization (photoCIDNP) NMR in combination with a stopped-flow.in situ mixing device developed in-house, we have been able to extract site-specific information on structurally ill-defined molten globular-and/or unfolded states.A recent example is the Trp-cage ultrafast folding miniprotein (TC5b), where pulse-labelling experiments that involve rapid in situ protein refolding have allowed dipolar cross-relaxation with hyperpolarized aromatic side chain nuclei in the unfolded state to be identified and quantified in the resulting folded-state spectrum.We fred that there is residual structure due to hydrophobic collapse in the unfolded state of this small protein, with strong inter-residue contacts between side chains that are relatively distant from one another in the native state.Prior structuring, even with the formation of non-native rather than native contacts, may be a feature associated with fast folding events in proteins.Moreover, the experimental features found in the unfolded state may in the future be useful for evaluating the parameters used in computational studies of unstructured proteins.