The folding rate is not retarded by populating an intermediate, which would be expected for a misfold state, but is accelerated, suggesting that the I state is productive and on-pathway.
Our results reveal a rich network of unfolding events, where the native state unfolds either in a two-state manner or by populating an intermediate state I, while the PF state unravels through a multitude of pathways, underscoring its structural heterogeneity.
Under tension, the Mg2+-bound state of NCS-1 unfolds and refolds in a three-state process by populating one intermediate state consisting of a folded C-domain and an unfolded N-domain.
Previous studies have also shown that ANTXR2 dimerization leads to an increase in the formation of PA8 in vitro, presumably by populating dimeric intermediates along the assembly pathway [21].
Therefore, we propose that ANTXRs, LF, and EF can stimulate PA oligomerization by populating dimeric PA intermediates, which are precursor intermediates in the PA oligomerization mechanism.
Since ANTXR2 dimerization enhances the formation of PA8, it was proposed that it may also facilitate assembly at the cell-surface by populating dimeric intermediates, because PA8 complexes are produced in that environment [21].
In this view, the enzyme product complex (EP) populates transiently an intermediate state (EP*) that favours the release of the product (E + P).
Whilst Im9 folds in a two-state transition at pH 7.0 and 10 °C, Im7 populates an on-pathway intermediate under these conditions.
During refolding from the fully denatured state, the γD-crystallin chains populate a partially folded intermediate, with the N-terminal domain disordered and the C-terminal domain nativelike.
Input-output coefficients populate matrix A (intermediate inputs) and row vectors k and l (factor inputs).
For Im9, increasing the helix propensity or hydrophobicity of specific regions, altering its sequence to incorporate just three residues from Im7, or changing the pH switches the folding mechanism of this protein from two to three state, by specifically stabilizing an intermediate common to both folding pathways such that it becomes visibly populated during folding [ 28,39,40].
