Scanning malleable transition state ensembles: comparing theory and experiment for folding protein U1A.

Using a variational free energy functional, we calculate the characteristics of the transition state ensembles (TSE) for the folding of protein U1A and investigate how they respond to thermal and mutational changes. The functional directly yields predicted chevron plots both for the wild-type protein and for various mutants. The detailed variations of the TSE and changes in chevron plots predicted by the theory agree reasonably well with the results of the experiments. We also show how to visualize the folding nuclei using 3D isodensity plots.