Mapping between the order of thermal denaturation and the shape of the critical line of mechanical unzipping in one-dimensional DNA models

In this Letter, we investigate the link between thermal denaturation and mechanical unzipping for two models of DNA, namely the Dauxois-Peyrard-Bishop model and a variant thereof we proposed recently. We show that the critical line that separates zipped from unzipped DNA sequences in mechanical unzipping experiments is a power-law in the temperature-force plane. We also prove that for the investigated models the corresponding critical exponent is proportional to the critical exponent alpha, which characterizes the behaviour of the specific heat in the neighbourhood of the critical temperature for thermal denaturation. (C) 2009 Elsevier B. V. All rights reserved.