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Thermodynamic Compensation in Peptides Following Liquid-Liquid Phase Separation
Riley J Workman1, B Montgomery Pettitt1
1Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555, United States.
The Journal of Physical Chemistry. B
|June 10, 2021
Summary
Liquid-liquid phase separation in proteins involves changes in entropy. This study models peptide phase transitions, finding that decreased interaction enthalpy compensates for lost backbone conformational entropy during droplet formation.
Area of Science:
- Biophysics
- Computational Biology
- Protein Science
Background:
- Liquid-liquid phase separation (LLPS) is crucial for cellular organization.
- Intrinsically disordered proteins (IDPs) are often involved in LLPS.
- Quantifying entropy changes in LLPS provides insight into phase transitions.
Purpose of the Study:
- To investigate the effect of residue sequence on peptide backbone conformational entropy during LLPS.
- To model LLPS of peptides using all-atom simulations.
- To explore how side chain variations influence droplet characteristics.
Main Methods:
- All-atom simulations of pentapeptide systems undergoing LLPS.
- Analysis of backbone conformational entropy changes during phase transitions.
- Comparison of four distinct pentapeptide sequences (GGGGG, GGQGG, GGNGG, GGVGG).
Main Results:
- Peptide-dense liquid droplet phases formed from supersaturated pentapeptide solutions.
- Aqueous to droplet transitions resulted in a loss of conformational entropy.
- Decreased interaction enthalpy compensated for the entropic loss in free energy.
Conclusions:
- Side chain composition significantly impacts LLPS droplet properties.
- Entropy loss during LLPS is energetically favorable due to enthalpy contributions.
- Computational modeling of peptide LLPS is a viable approach to study these phenomena.
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