We discuss the effects of external stress on the thermal denaturation of homogeneous DNA. Pulling double-stranded DNA at each end exerts a profound effect on the thermal denaturation, or melting, of a long segment of this molecule. We discuss the effects on this transition of a stretching force applied to opposite ends of the DNA, including full consideration of the consequences of excluded volume, the analysis of which is greatly simplified in this case. We find that in three dimensions the heat capacity acquires a logarithmic dependence on reduced temperature.

• Received 9 October 2007

DOI:https://doi.org/10.1103/PhysRevE.77.051903