title: Refolding and unfolding kinetics of the equilibrium folding intermediate of apomyoglobin.
abstract: Little is known about the kinetic process in which stable intermediates in protein folding are formed: whether their folding is highly cooperative (two-state) or weakly cooperative is controversial. We report here that the folding and unfolding kinetics of the pH 4-stable intermediate (I1) of apomyoglobin are measurable, in the millisecond time range, when monitored by stopped-flow measurements of tryptophan fluorescence. The kinetics confirm that folding of I1 is strongly cooperative, but there is a burst phase (missing amplitude) in unfolding. If the faster steps in unfolding of I1 can be measured directly by suitable fast-reaction methods, they will give information about the nature of the folding transition.
authors.affiliation: Department of Biochemistry, Stanford University Medical Center, California 94305-5307, USA.
authors.forename: M
authors.initials: M
authors.lastname: Jamin
authors.forename: R L
authors.initials: RL
authors.lastname: Baldwin
mesh_terms: D001059:Apoproteins / Q000737:chemistry*; D002942:Circular Dichroism; D005453:Fluorescence; D007700:Kinetics; D009211:Myoglobin / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D013997:Time Factors; D014508:Urea / Q000737:chemistry
chemical_list: D001059:Apoproteins; D009211:Myoglobin; C010857:apomyoglobin; D014508:Urea