title: Thermodynamics of polymolecular duplexes between phosphate-methylated DNA and natural DNA.
abstract: Phosphate-methylated (P.M.) DNA possesses a very high affinity for complementary natural DNA, as a result of the absence of interstrand electrostatic repulsions. In this study, a model system phosphate-methylated d[Cn] with natural d(Gk) (n less than k) is chosen for an investigation of the thermodynamic properties that determine duplex stability. The enthalpy change of a melting transition is shown to be considerably larger than is observed for corresponding natural DNA duplexes. It is found that delta Hn0 of GG/CC nearest neighbor pairwise interaction equals -15.6 kcal/mol, compared to -11.0 kcal/mol for the natural analog. The entropy change is strongly dependent on the length of the natural DNA strand and the number of phosphate-methylated DNA oligomers hybridized. The results are explained by means of a model in which a cooperative effect for subsequent hybridizations of phosphate-methylated DNA oligomers is assumed, thus giving additional stability.
authors: Department of Organic Chemistry, Eindhoven University of Technology, The Netherlands.
authors: M R
authors: MR
authors: Moody
authors: M H
authors: MH
authors: van Genderen
authors: H M
authors: HM
authors: Buck
mesh_terms: D004247:DNA / Q000737:chemistry*; D008745:Methylation; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D010710:Phosphates / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D010710:Phosphates; D004247:DNA