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On the complexation of proteins and polyelectrolytes
Fernando Luís B da Silva1, Mikael Lund, Bo Jönsson
1Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Av. do café, s/no., Universidade de São Paulo, 14040-903 Ribeirão Preto, SP, Brazil. fernando@fcfrp.usp.br
The Journal of Physical Chemistry. B
|March 3, 2006
Summary
Polyelectrolytes bind proteins even with the same charge, explained by charge regulation. Induced ionization creates strong attraction, overcoming repulsion and ion-dipole forces.
Area of Science:
- Biophysics
- Polymer Science
- Protein Chemistry
Background:
- Polyelectrolytes and proteins form complexes, sometimes despite similar charges.
- Existing theories attribute this to ion-dipole interactions overcoming repulsion.
Purpose of the Study:
- To propose and investigate charge regulation as the primary mechanism for protein-polyelectrolyte association.
- To quantify the contribution of induced charge interactions in protein-polymer complex formation.
Main Methods:
- Utilizing Monte Carlo simulations and perturbation theory.
- Investigating complexes of lysozyme, alpha-lactalbumin, and beta-lactoglobulin with polyelectrolytes.
- Analyzing the role of induced ionization of amino acid residues.
Main Results:
- Charge regulation, via induced ionization, drives strong protein-polyelectrolyte attraction.
- This charge-induced charge interaction is comparable to or stronger than ion-dipole forces.
- The protein charge capacitance (Z2-Z2) governs the magnitude of induced charge.
Conclusions:
- Charge regulation provides a more accurate explanation for protein-polyelectrolyte complexation than previously thought.
- Induced ionization is a significant factor in these interactions.
- The protein charge capacitance is a key parameter for understanding and predicting these associations.