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In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
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Assembly and Characterization of Polyelectrolyte Complex Micelles
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Effect of Protein Surface Charge Distribution on Protein-Polyelectrolyte Complexation.

Sieun Kim1, Hursh V Sureka1, A Basak Kayitmazer2

  • 1Department of Chemical Engineering, Massachusetts Institute of Technology, 02139 Cambridge, Massachusetts, United States.

Biomacromolecules
|July 17, 2020
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Summary
This summary is machine-generated.

Protein surface charge patches significantly influence coacervation, driving complex formation and phase behavior. Increased charge patchiness promotes protein-polymer complexation and aggregation, impacting biomolecular condensates.

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Area of Science:

  • Biochemistry
  • Biophysics
  • Materials Science

Background:

  • Protein surface charge distribution is hypothesized to influence coacervation behavior.
  • Charge anisotropy may explain coacervation outside a protein's isoelectric point.

Purpose of the Study:

  • To investigate the role of protein surface charge patchiness in driving coacervation.
  • To quantify the relationship between charge patchiness and protein-polymer complex formation and phase behavior.

Main Methods:

  • Engineered superfolder green fluorescent protein mutants with varied surface charge distributions but constant net charge.
  • Utilized a patchiness parameter to quantify protein surface charge correlation.
  • Studied complexation and phase behavior with strong and weak polyelectrolytes.

Main Results:

  • Proteins with higher patchiness parameters exhibited increased complexation with polyelectrolytes.
  • Increasing protein charge patchiness promoted macrophase separation and soluble aggregate formation.
  • The effect of patchiness on phase behavior was dependent on the type of polyelectrolyte used.

Conclusions:

  • Protein surface charge patchiness is a critical determinant of coacervation and phase behavior.
  • Charge patchiness, rather than net charge alone, governs protein-polymer interactions.
  • Understanding charge distribution is key for predicting and controlling biomolecular condensate formation.