Direct observation of large temperature fluctuations during DNA thermal denaturation

TL;DR

This study directly measures large low-frequency temperature fluctuations during DNA thermal denaturation, revealing dynamic equilibrium between denatured and closed base pairs that cause significant fluctuations only in the transition range.

Contribution

It provides the first direct measurement of large temperature fluctuations during DNA denaturation and links them to dynamic coexistence of DNA states.

Findings

Large fluctuations occur only during denaturation transition

Fluctuations depend on wait time and vanish within hours

Fluctuations are due to coexistence of denatured and closed base pairs

Abstract

In this paper we report direct measurement of large low frequency temperature fluctuations in double stranded (ds) DNA when it undergoes thermal denaturation transition. The fluctuation, which occurs only in the temperature range where the denaturation occurs, is several orders more than the expected equilibrium fluctuation. It is absent in single stranded (ss) DNA of the same sequence. The fluctuation at a given temperature also depends on the wait time and vanishes in a scale of few hours. It is suggested that the large fluctuation occurs due to coexisting denaturated and closed base pairs that are in dynamic equilibrium due to transition through a potential barrier in the scale of 25-30k_{B}T_{0}(T_{0}=300K).