Related Experiment Videos
Characterization of transient intermediates in lysozyme folding with time-resolved small-angle X-ray scattering
D J Segel1, A Bachmann, J Hofrichter
1Department of Physics, Stanford University, Stanford, CA, 94305, USA.
Journal of Molecular Biology
|May 18, 1999
Summary
Protein refolding involves rapid chain collapse, forming a globular shape with accessible hydrophobic side-chains. A later intermediate resembles native lysozyme but is less stable.
Area of Science:
- Biophysics
- Protein folding dynamics
- Structural biology
Background:
- Protein folding is crucial for biological function.
- Understanding the intermediate states of protein folding is key to deciphering the process.
- Lysozyme is a model protein for studying folding mechanisms.
Purpose of the Study:
- To investigate the early events in lysozyme refolding.
- To characterize the structural changes during lysozyme folding using time-resolved techniques.
- To compare the properties of folding intermediates with the native and unfolded states.
Main Methods:
- Synchrotron radiation X-ray scattering
- Stopped-flow and continuous-flow mixing
- Time-resolved fluorescence spectroscopy
Main Results:
- A rapid, major chain collapse occurs within milliseconds, achieving 50% of the radius of gyration change and a globular shape.
- The collapsed state exhibits solvent-accessible hydrophobic side-chains.
- A subsequent intermediate forms with helical structure, native-like size and shape, and a buried hydrophobic core, but is only marginally stable.
Conclusions:
- Early protein folding is characterized by a rapid collapse and subsequent structural rearrangements.
- The intermediate states formed during folding can possess native-like structural features but differ significantly in stability.
- These findings provide insights into the energy landscape and pathways of protein folding.