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Specific non-native hydrophobic interactions in a hidden folding intermediate: implications for protein folding
Hanqiao Feng1, Jiro Takei, Rebecca Lipsitz
1Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Biochemistry
|October 29, 2003
Summary
Researchers determined the high-resolution structure of a protein folding intermediate. This intermediate, from Rd-apocyt b(562), revealed non-native hydrophobic interactions, challenging previous assumptions about protein folding pathways.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Dynamics
Background:
- Protein folding intermediates are typically studied assuming native-like conformations.
- Characterization often relies on hydrogen exchange and protein engineering methods.
Purpose of the Study:
- To determine the high-resolution structure of a partially unfolded protein folding intermediate.
- To investigate the conformational properties and interactions within this intermediate.
Main Methods:
- Multidimensional Nuclear Magnetic Resonance (NMR) spectroscopy was employed.
- Stabilization of the folding intermediate was achieved for structural determination.
Main Results:
- A high-resolution structure of a folding intermediate of the four-helix bundle protein Rd-apocyt b(562) was determined.
- The intermediate exhibits partial native-like secondary structure and backbone topology.
- Significant non-native hydrophobic interactions were identified within the intermediate structure.
Conclusions:
- Non-native hydrophobic interactions may be common in partially folded protein states.
- These interactions can influence the interpretation of protein engineering studies.
- The rapid repair of non-native interactions, even after the rate-limiting step, suggests they do not typically impede folding kinetics.