Influence of supercoiling on the disruption of dsDNA.
We propose that supercoiling energizes double-stranded DNA (dsDNA) so as to facilitate thermal fluctuations to an unzipped state. We support this with a model of two elastic rods coupled via forces that represent base-pair interactions. Supercoiling is shown to lead to a distention of base pairs over a short span of dsDNA. This enhances the thermal probability for their disruption. The localized region of distention is analogous to a soliton. Our theory permits the development of an analogy between the unzipping transition and a second-order phase transition, for which the possibility of a new set of critical exponents is identified.
Chitanvis
Shirish M
SM
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. shirish@lanl.gov
Welch
Paul M
PM
D001482:Base Composition; D020029:Base Pairing; D002627:Chemistry, Physical / Q000379:methods; D004247:DNA / Q000737:chemistry*; D004278:DNA, Superhelical / Q000737:chemistry*; D004926:Escherichia coli / Q000378:metabolism; D006860:Hydrogen Bonding; D008956:Models, Chemical; D015233:Models, Statistical; D008968:Molecular Conformation; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D011336:Probability; D013696:Temperature; D013816:Thermodynamics
D004278:DNA, Superhelical; D004247:DNA