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pH-jump-induced folding and unfolding studies of barstar: evidence for multiple folding and unfolding pathways (2001)
| Content Provider | CiteSeerX |
|---|---|
| Author | Rami, Bhadresh R. Udgaonkar, Jayant B. |
| Abstract | ABSTRACT: Equilibrium and kinetic characterization of the high pH-induced unfolding transition of the small protein barstar have been carried out in the pH range 7-12. A mutant form of barstar, containing a single tryptophan, Trp 53, completely buried in the core of the native protein, has been used. It is shown that the protein undergoes reversible unfolding above pH 10. The pH 12 form (the D form) appears to be as unfolded as the form unfolded by 6 M guanidine hydrochloride (GdnHCl) at pH 7 (the U form): both forms have similar fluorescence and far-UV circular dichroism (CD) signals and have similar sizes, as determined by dynamic light scattering and size-exclusion chromatography. No residual structure is detected in the D form: addition of GdnHCl does not alter its fluorescence and far-UV CD properties. The fluorescence signal of Trp 53 has been used to monitor folding and unfolding kinetics. The kinetics of folding of the D form in the pH range 7-11 are complex and are described by four exponential processes, as are the kinetics of unfolding of the native state (N state) in the pH range 10.5-12. Each kinetic phase of folding decreases in rate with increase in pH from 7 to 10.85, and each kinetic phase of unfolding decreases in rate with decrease in pH from 12 to 10.85. At pH 10.85, the folding and unfolding rates for any particular kinetic phase are identical and minimal. The two slowest phases of folding and unfolding have identical kinetics whether measured by Trp 53 fluorescence or by mean residue ellipticity at 222 |
| File Format | |
| Journal | Biochemistry |
| Language | English |
| Publisher Date | 2001-01-01 |
| Access Restriction | Open |
| Subject Keyword | Multiple Folding Ph-jump-induced Folding Unfolding Study Unfolding Pathway Ph Range Kinetic Phase Native State Identical Kinetics Fluorescence Signal Residual Structure Similar Size Small Protein Barstar Kinetic Characterization Exponential Process Unfolding Rate High Ph-induced Unfolding Transition Size-exclusion Chromatography Mutant Form Far-uv Circular Dichroism Far-uv Cd Property Ph Range 7-12 Single Tryptophan Native Protein Similar Fluorescence Guanidine Hydrochloride Unfolding Kinetics Mean Residue Ellipticity Particular Kinetic Phase |
| Content Type | Text |
| Resource Type | Article |
