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Binding of ionic ligands to polyelectrolytes
1Department of Pharmaceutical Chemistry, University of California, San Francisco 94143, USA.
Biophysical Journal
|October 1, 1996
Summary
This study presents a Poisson-Boltzmann model to predict how ionic ligands bind to charged polymers like DNA. The model accurately forecasts binding constants and salt effects for various ligand-polyelectrolyte interactions.
Area of Science:
- Biophysical Chemistry
- Polymer Science
- Computational Chemistry
Background:
- Ionic ligands interact with charged polymers, including DNA and polysaccharides.
- Understanding these interactions is crucial for molecular biology and materials science.
Purpose of the Study:
- To develop a theoretical framework for calculating binding constants of ionic ligands to polyelectrolytes.
- To investigate the influence of ligand charge and salt concentration on binding affinity.
Main Methods:
- A Poisson-Boltzmann treatment was employed to model ligand-polyelectrolyte binding.
- Lattice statistics were used to account for the conformations of flexible chain ligands.
- The model was applied to various systems, including Mg(2+) ions with polynucleotides and hexamine cobalt(III) with DNA.
Main Results:
- The developed theory successfully predicts the salt dependence of binding constants for multiple ligand-polyelectrolyte systems.
- Binding free energies were accurately computed for interactions such as polyamines with T7 DNA and oligolysines with poly(U).
- The model requires one parameter (distance of closest approach) for absolute binding constant calculations.
Conclusions:
- The Poisson-Boltzmann approach provides a robust method for predicting ionic ligand-polyelectrolyte binding.
- The model offers insights into the thermodynamics of these interactions, with good predictions for binding entropies and enthalpies in some cases.