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Updated: Jan 24, 2026
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Isothermal Titration Calorimetry for Measuring Macromolecule-Ligand Affinity
Published on: September 7, 2011
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Osmolyte-Induced Collapse of a Charged Macromolecule
Mrinmoy Mukherjee1, Jagannath Mondal1
1Center for Interdisciplinary Sciences , Tata Institute of Fundamental Research , Hyderabad 500107 , India.
The Journal of Physical Chemistry. B
|May 16, 2019
Summary
Trimethylamine N-oxide (TMAO) can stabilize or destabilize polymer collapse depending on charge. Introducing charges can initially hinder collapse, but further addition may restore stabilization, with effects varying by charge density.
Area of Science:
- Chemical Physics
- Polymer Science
- Biophysical Chemistry
Background:
- Osmolytes influence macromolecular conformation, but their effect on charged polymers is less understood.
- Trimethylamine N-oxide (TMAO) is a common osmolyte with known effects on protein and polymer structures.
- The role of electrostatic charges within macromolecules on osmolyte-induced conformational changes requires further investigation.
Purpose of the Study:
- To investigate the influence of incorporated charges on trimethylamine N-oxide (TMAO)-induced polymer collapse.
- To elucidate the relationship between charge density, charge distribution, and osmolyte-induced conformational changes in polymers.
- To understand the molecular mechanisms governing TMAO-polymer interactions in the presence of charges.
Main Methods:
- Computational simulation of a charge-neutral polymer model.
- Systematic variation of the number and density of oppositely charged monomeric beads.
- Free-energy-based analysis to quantify conformational stability.
- Molecular-level analysis of polymer-TMAO interactions.
Main Results:
- A nonmonotonic trend was observed in TMAO-induced polymer collapse at low charge densities.
- Initial introduction of charges destabilized collapse, but further addition led to re-stabilization.
- Increasing charge density diminished the nonmonotonic trend, with TMAO acting as a denaturant at high charge.
- Differential interactions of TMAO's nitrogen and oxygen atoms with charged beads, alongside competing dispersion and electrostatic forces, dictate the observed trends.
Conclusions:
- The conformational preference of polymers in TMAO solutions is significantly modulated by incorporated charges.
- Charge density and distribution play critical roles in determining whether TMAO stabilizes or denatures a polymer.
- Understanding these charge-dependent interactions is crucial for predicting macromolecular behavior in biological and chemical systems.
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