Measurement of the Phase Diagram of DNA Unzipping in the Temperature- Force Plane

TL;DR

This study experimentally maps the phase boundary of DNA unzipping in the temperature-force plane, revealing deviations from existing models and providing new insights into DNA stability under force.

Contribution

It provides the first experimental phase diagram of DNA unzipping across a range of temperatures and forces, highlighting discrepancies with theoretical predictions.

Findings

Measured the minimum force to unzip DNA at various temperatures.

Identified deviations between experimental data and existing models.

Provided new data on DNA free energy in non-denaturing conditions.

Abstract

We separate double stranded lambda phage DNA by applying a fixed force at a constant temperature ranging from 15C to 50C, and measure the minimum force required to separate the two strands, providing the first experimental determination of the phase boundary between single stranded DNA and double stranded DNA in the temperature- force plane. The measurements also offer information on the free energy of dsDNA at temperatures where dsDNA does not thermally denature in the absence of force. While parts of the phase diagram can be explained using existing models and free energy parameters, others deviate significantly. Possible reasons for the deviations between theory and experiment are considered.