Conformational dynamics and ensembles in protein folding

Recent experimental developments are changing the ways we interpret experimental data in protein folding, leading to a closer connection with theory and an improved understanding of some long-standing questions in the field. We now have a basic roadmap of the types of polypeptide motions and timescales that are relevant to the various folding stages. The folding barriers estimated with a variety of independent methods are consistently small, indicating that several fast-folding proteins are near or within the downhill folding regime. Finally, the structural and statistical analysis of global downhill folding is promising to open a new avenue of research in which folding mechanisms and the networks of noncovalent interactions that stabilize native structures are directly resolved in equilibrium experiments of nonmutated proteins.