Denaturation transition of stretched DNA

TL;DR

This paper extends the Poland-Scheraga model to include external stretching forces, revealing a force-induced DNA denaturation transition and providing a phase diagram that aligns with experimental observations.

Contribution

It introduces a generalized model for DNA denaturation under force, deriving a new loop exponent value and characterizing the transition as second order in three dimensions.

Findings

Force induces DNA denaturation at lower temperatures.

The phase diagram maps temperature and force effects on DNA stability.

The transition is second order with a specific loop exponent value.

Abstract

We generalize the Poland-Scheraga model to consider DNA denaturation in the presence of an external stretching force. We demonstrate the existence of a force-induced DNA denaturation transition and obtain the temperature-force phase diagram. The transition is determined by the loop exponent $c$ for which we find the new value $c=4\nu-1/2$ such that the transition is second order with $c=1.85<2$ in $d=3$. We show that a finite stretching force $F$ destabilizes DNA, corresponding to a lower melting temperature $T(F)$, in agreement with single-molecule DNA stretching experiments.