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Automated Hydrophobic Interaction Chromatography Column Selection for Use in Protein Purification
Published on: September 21, 2011
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Selection for Protein Stability Enriches for Epistatic Interactions.
Anna Posfai1, Juannan Zhou2, Joshua B Plotkin3
1Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA. posfai@cshl.edu.
Genes
|August 24, 2018
Summary
Most protein stabilities are near the folding threshold due to an entropic pull. Even small non-additive effects from mutations are crucial for maintaining protein structures, compatible with observed additivity.
Area of Science:
- Protein biophysics
- Molecular evolution
- Computational biology
Background:
- The marginal thermodynamic stability of proteins is classically explained by an entropic pull in sequence space, suggesting most foldable proteins exist near their folding threshold.
- Observed effects of mutations on protein folding free energy are generally considered nearly additive and evolutionarily conserved.
Purpose of the Study:
- To extend the marginal stability argument to predict epistatic interactions in protein sequences.
- To investigate the compatibility of non-additive contributions to folding free energy with the observed near-additivity of mutation effects.
Main Methods:
- Theoretical modeling of protein sequence space.
- Computational simulations of mutation effects on protein folding free energy.
- Analytical derivations of free energy contributions.
Main Results:
- The marginal stability argument predicts specific patterns of epistatic interactions.
- Even minimal deviations from additivity in folding free energy are sufficient to maintain native protein structures.
- These findings reconcile the apparent additivity of mutation effects with the necessity of non-additive contributions.
Conclusions:
- Non-additive epistatic interactions are essential for protein structure stability, despite the appearance of additivity in mutation effects.
- The entropic pull mechanism, when extended to include epistasis, provides a framework for understanding protein sequence space and stability.
- Future research should focus on quantifying these non-additive effects in real protein systems.
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