BIOT 18 |
| The ultra-fast-folding subdomain of the chicken-villin headpiece (villin) is the smallest, naturally-occurring protein that folds autonomously, making it feasible to directly compare experimental folding kinetics with theoretical and computational studies. We have studied the folding kinetics of villin as a function of temperature and guanidinium chloride (GdmCl) concentration using nanosecond laser temperature-jump measurements. At low GdmCl concentrations, the observed relaxation is bi-exponential, consisting of a fast (~100ns) relaxation and a slow (~5micro) phase that corresponds to the unfolding/refolding transition. The relative amplitude of the fast phase decreases monotonically from > 50% in water to ~ 10% in 1M GdmCl. At high GdmCl concentrations there is only a single slow phase. The GdmCl dependence of the folding (slow) relaxation rate is very weak, indicating the presence of a very small barrier to folding. Various quantitative estimations of the barrier height will be presented, and the possibility of “downhill” or barrier-less folding discussed. |
|
Biophysical and Biomolecular Symposium: Protein Folding & Characterization
8:00 AM-11:10 AM, Sunday, August 19, 2007 BCEC -- 106, Oral
Division of Biochemical Technology |