title: Phi-value analysis for ultrafast folding proteins by NMR relaxation dispersion.
abstract: Proteins that fold rapidly, on the (sub-) microsecond time scale, offer the prospect of direct comparison between experimental data and molecular dynamics simulations. However, experimental studies for such proteins frequently are hindered because folding rates are too fast to measure using conventional stopped-flow methods. To overcome this impediment, NMR spin relaxation dispersion experiments are used to quantify mutational effects on kinetics (DeltaDeltaG(o)), stability (DeltaDeltaG(o)), and phi-values (DeltaDeltaG(dagger)/DeltaDeltaG(o)) for proteins exhibiting chemical exchange line broadening that is fast on the NMR chemical shift time scale. The accuracy of phi-value analysis is enhanced because mutational effects on denatured or intermediate states can be detected through changes in line broadening. The transition and intermediate states of the villin headpiece domain, HP67, are characterized in varying solvent conditions to validate the method.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Columbia University, 630 West 168th Street, New York, New York 10032, USA.
authors.forename: Jae-Hyun
authors.initials: JH
authors.lastname: Cho
authors.forename: Nichole
authors.initials: N
authors.lastname: O'Connell
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Raleigh
authors.forename: Arthur G
authors.initials: AG
authors.lastname: Palmer
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D011506:Proteins