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Complex folding kinetics of a multidomain protein.
Sarah Batey1, Kathryn A Scott, Jane Clarke
1Department of Chemistry, MRC Centre for Protein Engineering, University of Cambridge, Cambridge CB2 1EW, United Kingdom.
Biophysical Journal
|January 3, 2006
Summary
Domain interactions in spectrin proteins significantly impact folding kinetics. Cooperative folding of tandem spectrin domains demonstrates a single rate-determining step, enhancing protein stability.
Area of Science:
- Biophysics
- Structural Biology
- Protein Dynamics
Background:
- Spectrin domains are common three-helix bundles found in tandem arrays.
- Equilibrium studies indicate neighboring spectrin domains stabilize each other.
Purpose of the Study:
- To investigate the kinetic effects of domain:domain interactions in spectrin.
- To understand the folding behavior of a tandem pair of spectrin domains (R1617).
Main Methods:
- Utilized single- and double-jump stopped-flow experiments.
- Monitored protein folding using circular dichroism and fluorescence.
- Employed mutant proteins to analyze complex folding kinetics.
Main Results:
- Identified a single rate-determining step for both folding and unfolding of the two-domain protein.
- Observed individual domain folding and unfolding, yet cooperative behavior of the entire protein.
- Demonstrated that domain interactions profoundly influence kinetic behavior.
Conclusions:
- Cooperative folding of tandem spectrin domains enhances protein stability and efficiency.
- Results suggest caution when extrapolating single-domain behavior to multidomain proteins.
- Multidomain spectrin functions as more than the sum of its individual parts.