Ashkin-Teller formalism for elastic response of DNA molecule to external force and torque

TL;DR

This paper introduces an Ashkin-Teller like model to describe the elastic response of DNA to external forces and torques, capturing phase transitions and structural properties.

Contribution

It develops a unified formalism for DNA elasticity, including both double-stranded and single-stranded forms, and provides a phase diagram for DNA structural transitions.

Findings

Identifies the B to S transition induced by stretching and twisting.

Calculates the folding angle of dsDNA as 59.2 degrees.

Establishes a clear relation between DNA structure and its elastic response.

Abstract

We propose an Ashkin-Teller like model for elastic response of DNA molecule to external force and torque. The base-stacking interaction is described in a simple and uniform way. We obtain the phase diagram of dsDNA, and in particular, the transition from B form to the S state induced by stretching and twisting. The elastic response of the ssDNA is presented also in a unified formalism. The close relation of dsDNA molecule structure with elastic response is shown clearly. The calculated folding angle of the dsDNA molecule is $59.2^o$.