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Updated: May 26, 2026

Stable DNA Motifs, 1D and 2D Nanostructures Constructed from Small Circular DNA Molecules
Published on: April 12, 2019
Denaturation of circular DNA: supercoil mechanism
Amir Bar1, Alkan Kabakçoğlu, David Mukamel
1Department of Physics of Complex Systems, The Weizmann Institute of Science, Rehovot 76100, Israel.
Abstract:
The denaturation transition which takes place in circular DNA is analyzed by extending the Poland-Scheraga (PS) model to include the winding degrees of freedom. We consider the case of a homopolymer whereby the winding number of the double-stranded helix, released by a loop denaturation, is absorbed by supercoils. We find that as in the case of linear DNA, the order of the transition is determined by the loop exponent c. However the first-order transition displayed by the PS model for c>2 in linear DNA is replaced by a continuous transition with arbitrarily high order as c approaches 2, while the second-order transition found in the linear case in the regime 1
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