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Thermodynamics of Membrane Protein Folding Measured by Fluorescence Spectroscopy
Published on: April 28, 2011
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WW domain folding complexity revealed by infrared spectroscopy
Caitlin M Davis1, R Brian Dyer
1Department of Chemistry, Emory University , Atlanta, Georgia 30322, United States.
Biochemistry
|August 15, 2014
Summary
Combining infrared and fluorescence spectroscopy reveals distinct phases of protein folding dynamics. This multi-probe approach clarifies the FBP28 WW domain folding pathway, identifying an intermediate molten globule state.
Area of Science:
- Biophysics
- Protein dynamics
- Spectroscopy
Background:
- Protein folding is crucial for function, but its dynamics are complex.
- Tryptophan fluorescence is sensitive to both global and local protein changes.
- Infrared (IR) spectroscopy probes protein backbone secondary structure.
Purpose of the Study:
- To investigate the folding dynamics of the FBP28 WW domain.
- To demonstrate the advantages of using complementary probes (IR and fluorescence spectroscopy).
- To resolve distinct kinetic phases in protein folding.
Main Methods:
- Laser-induced temperature jumps coupled with fluorescence and IR spectroscopy.
- Submillisecond time-resolved measurements.
- Analysis of IR amide I bands to probe β-sheets and β-turns.
Main Results:
- Observed three distinct kinetic phases in FBP28 WW domain folding.
- Fastest phase corresponds to β-turn relaxation; slowest phase matches fluorescence data.
- Mutant studies suggest an intermediate dry molten globule state.
Conclusions:
- Multiple spectroscopic probes provide a more comprehensive understanding of protein folding.
- The slowest folding step involves side-chain packing into the native state.
- IR and fluorescence spectroscopy reveal complex, multi-phasic folding dynamics.
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