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Updated: Jan 26, 2026
07:35
Non-chromatographic Purification of Recombinant Elastin-like Polypeptides and their Fusions with Peptides and Proteins from Escherichia coli
Published on: June 9, 2014
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Ionic polypeptide tags for protein phase separation.
Rachel A Kapelner1, Allie C Obermeyer1
1Department of Chemical Engineering , Columbia University , New York , NY 10027 , USA . Email: aco2134@columbia.edu ; Tel: +1-212-853-1315.
Chemical Science
|April 19, 2019
Summary
Short ionic tags enable globular proteins to undergo liquid-liquid phase separation, expanding applications in protein therapeutics and biocatalysis. This complex coacervation is tunable by protein design.
Area of Science:
- Biochemistry
- Materials Science
- Chemical Engineering
Background:
- Complex coacervation, a liquid-liquid phase separation of oppositely charged polyelectrolytes, is gaining interest for protein applications.
- Globular proteins often fail to phase separate or do so under limited conditions, hindering their use in therapeutics, purification, and biocatalysis.
Purpose of the Study:
- To explore protein design factors influencing complex coacervation.
- To develop and assess polyionic coacervation tags for promoting protein phase separation.
- To enable globular protein liquid-liquid phase separation under physiological conditions.
Main Methods:
- Engineered proteins with polyionic tags were designed based on charge distribution and disordered regions.
- Phase behavior was evaluated using a strong polycation, poly(4-vinyl N-methyl pyridinium iodide).
- Salt dependence and residue ratios were analyzed to predict coacervation behavior.
Main Results:
- Proteins with ionic tags formed liquid coacervate droplets, unlike solid precipitates from isotropically charged variants.
- Ionic tags facilitated phase separation at higher salt concentrations.
- Short polypeptide tags (6-18 amino acids) induced liquid-liquid phase separation in globular proteins at physiological conditions.
Conclusions:
- Short, ionic polypeptide sequences can effectively drive complex coacervation in globular proteins.
- This approach expands the utility of proteins in therapeutics, purification, and biocatalysis.
- The findings provide a model system for designing proteins with tunable phase separation properties.
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