Theoretical studies of d(A:T)-based parallel-stranded DNA duplexes.
Poly d(A:T) parallel-stranded DNA duplexes based on the Hoogsteen and reverse Watson-Crick hydrogen bond pairing are studied by means of extensive molecular dynamics (MD) simulations and molecular mechanics coupled to Poisson-Boltzmann (MM-PB/SA) calculations. The structural, flexibility, and reactivity characteristics of Hoogsteen and reverse Watson-Crick parallel duplexes are described from the analysis of the trajectories. Theoretical calculations show that the two parallel duplexes are less stable than the antiparallel Watson-Crick duplex. The difference in stability between antiparallel and parallel duplexes increases steadily as the length of the duplex increases. The reverse Watson-Crick arrangement is slightly more stable than the Hoogsteen duplex, the difference being also increased linearly with the length of the duplex. A subtle balance of intramolecular and solvation terms is responsible for the preference of a given helical structure.
Cubero
E
E
Departament de Bioquímica i Biologia Molecular, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1, Barcelona 08028, Spain.
Luque
F J
FJ
Orozco
M
M
D004247:DNA / Q000737:chemistry*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011067:Poly dA-dT / Q000737:chemistry*
D011067:Poly dA-dT; D004247:DNA