title: Thermodynamics of twisted DNA with solvent interaction.
abstract: The imaginary time path integral formalism is applied to a nonlinear Hamiltonian for a short fragment of heterogeneous DNA with a stabilizing solvent interaction term. Torsional effects are modeled by a twist angle between neighboring base pairs stacked along the molecule backbone. The base pair displacements are described by an ensemble of temperature dependent paths thus incorporating those fluctuational effects which shape the multisteps thermal denaturation. By summing over ~10(7)-10(8) base pair paths, a large number of double helix configurations is taken into account consistently with the physical requirements of the model potential. The partition function is computed as a function of the twist. It is found that the equilibrium twist angle, peculiar of B-DNA at room temperature, yields the stablest helicoidal geometry against thermal disruption of the base pair hydrogen bonds. This result is corroborated by the computation of thermodynamical properties such as fractions of open base pairs and specific heat.
authors.affiliation: School of Science and Technology, CNISM, Università di Camerino, I-62032 Camerino, Italy. marco.zoli@unicam.it
authors.forename: Marco
authors.initials: M
authors.lastname: Zoli
mesh_terms: D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D006860:Hydrogen Bonding; D008962:Models, Theoretical; D012997:Solvents / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D012997:Solvents; D004247:DNA