Native state energetics of the Src SH2 domain: evidence for a partially structured state in the denatured ensemble.

ABSTRACT: We have defined the free-energy profile of the Src SH2 domain using a variety of biophysical techniques. Equilibrium and kinetic experiments monitored by tryptophan fluorescence show that Src SH2 is quite stable and folds rapidly by a two-state mechanism, without populating any intermediates. Native state hydrogen-deuterium exchange confirms this two-state behavior; we detect no cooperative partially unfolded forms in equilibrium with the native conformation under any conditions. Interestingly, the apparent stability of the protein from hydrogen exchange is 2 kcal/mol greater than the stability determined by both equilibrium and kinetic studies followed by fluorescence. Native-state proteolysis demonstrates that this "super protection" does not result from a deviation from the linear extra

SUBMITTER: Wildes D 

PROVIDER: S-EPMC2242571 | biostudies-literature | 2006 Jul

REPOSITORIES: biostudies-literature