title: DNA-DNA interaction beyond the ground state.
abstract: The electrostatic interaction potential between DNA duplexes in solution is a basis for the statistical mechanics of columnar DNA assemblies. It may also play an important role in recombination of homologous genes. We develop a theory of this interaction that includes thermal torsional fluctuations of DNA using field-theoretical methods and Monte Carlo simulations. The theory extends and rationalizes the earlier suggested variational approach which was developed in the context of a ground state theory of interaction of nonhomologous duplexes. It shows that the heuristic variational theory is equivalent to the Hartree self-consistent field approximation. By comparison of the Hartree approximation with an exact solution based on the QM analogy of path integrals, as well as Monte Carlo simulations, we show that this easily analytically-tractable approximation works very well in most cases. Thermal fluctuations do not remove the ability of DNA molecules to attract each other at favorable azimuthal conformations, neither do they wash out the possibility of electrostatic "snap-shot" recognition of homologous sequences, considered earlier on the basis of ground state calculations. At short distances DNA molecules undergo a "torsional alignment transition," which is first order for nonhomologous DNA and weaker order for homologous sequences.
authors.affiliation: Department of Chemistry, Faculty of Physical Sciences, Imperial College London, SW7 2AZ London, United Kingdom.
authors.forename: D J
authors.initials: DJ
authors.lastname: Lee
authors.forename: A
authors.initials: A
authors.lastname: Wynveen
authors.forename: A A
authors.initials: AA
authors.lastname: Kornyshev
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D001665:Binding Sites; D003198:Computer Simulation; D003460:Crystallization / Q000379:methods; D004247:DNA / Q000032:analysis / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D015233:Models, Statistical; D008969:Molecular Sequence Data; D009010:Monte Carlo Method; D011789:Quantum Theory; D017422:Sequence Analysis, DNA / Q000379:methods*
chemical_list: D046911:Macromolecular Substances; D004247:DNA