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Updated: Jan 17, 2026
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Spatial Separation of Molecular Conformers and Clusters
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Phase Separation of Positively Charged Polypeptide Solutions: Interplay between Electrostatics and Nonelectrostatic
Yajing Wang1, Yu Xin1, Pengfei Zhang1
1State Key Laboratory of Advanced Fiber Materials, Center for Advanced Low-Dimension Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China.
Biomacromolecules
|September 18, 2025
Summary
This study reveals how electrostatics and specific interactions drive liquid-liquid phase separation (LLPS) in charged polypeptides. Findings explain LLPS regulation by factors like salt concentration and molecular interactions.
Area of Science:
- Biophysics
- Physical Chemistry
- Molecular Biology
Background:
- Liquid-liquid phase separation (LLPS) of biomacromolecules is crucial for cellular functions.
- The driving forces behind LLPS are not fully understood.
Purpose of the Study:
- To investigate the influence of electrostatics and specific interactions on LLPS in charged polypeptide solutions.
- To develop a theoretical framework for analyzing LLPS mechanisms.
Main Methods:
- Developed a mean-field theory combining Debye-Hückel correlation, chain connectivity perturbation, and the sticker-spacer model.
- Analyzed salt-free and salty solutions.
- Validated findings with experimental data and molecular dynamics simulations.
Main Results:
- In salt-free solutions, LLPS at moderate charge requires strong electrostatic correlation.
- Salty solutions without specific interactions show a closed-loop miscibility gap.
- Increased specific interaction strength or salt concentration promotes LLPS.
Conclusions:
- Electrostatic correlation, counterion entropy, excluded volume, and specific interactions intricately regulate polypeptide LLPS.
- The developed theory provides insights into LLPS phenomena in biological systems.
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