Kinetic evidence for folding and unfolding intermediates in staphylococcal nuclease

Protein folding research often finds complex kinetic behavior which shows that unfolded molecules take several stages to convert to the fully native form. A Pro- variate of SNase's unfolding and folding kinetic mechanism was characterized using stopped-flow fluorescence methods, with alanines and glycines used in place of six proline residues. The folding kinetics still demonstrate a complex denaturant dependence, even though complicating factors such as prolines have been removed. A sequential four-state folding mechanism can be used to model the primary stages in unfolding and folding.