title: DNA-RNA hybrid secondary structures.
abstract: DNA-RNA and DNA-DNA duplexes are even more polymorphic than observed previously. DNA-RNA hybrids can have secondary structures like A-DNA or A-RNA, but double helices of the synthetic DNA-RNA hybrids poly(dA) X poly(rU) and poly(dI) X poly(rC), respectively, form 11-fold and 10-fold double-helical structures in which the two chains have quite different conformations. Extensive X-ray fiber diffraction analyses show that in both structures the DNA chains have C-2'-endo-puckered furanose rings, while the anti-parallel RNA chains have C-3'-endo-puckered rings. The bidirectional properties of such duplexes may be important in the transfer of biological information from nucleic acids.
mesh_terms: D001482:Base Composition; D004247:DNA; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009692:Nucleic Acid Heteroduplexes; D011089:Polydeoxyribonucleotides; D011119:Polynucleotides; D012313:RNA; D014961:X-Ray Diffraction
chemical_list: D009692:Nucleic Acid Heteroduplexes; D011089:Polydeoxyribonucleotides; D011119:Polynucleotides; D012313:RNA; D004247:DNA