Phase diagram of mechanically stretched DNA: The salt effect

TL;DR

This study models how salt concentration influences the mechanical unzipping of DNA, showing that increased salt stabilizes the DNA strands and affects the critical force needed for unzipping, aligning well with experimental data.

Contribution

It introduces a modified nonlinear Hamiltonian incorporating solvent and salt effects to predict DNA unzipping behavior under mechanical stress.

Findings

Melting temperature varies with salt concentration.

Critical unzipping force depends on salt levels.

Phase diagrams match experimental results.

Abstract

The cations, in form of salt, present in the solution containing DNA play a crucial role in the opening of two strands of DNA. We use a simple non linear model and investigate the role of these cations on the mechanical unzipping of DNA. The Hamiltonian is modified to incoporate the solvent effect and the cations present in the solution. We calculate the melting temperature as well as the critical force that is required to unzip the DNA molecule as a function of salt concentration of the solution. The phase diagrams are found to be in close agreement with the experimental phase diagrams.