title: Salt-induced conformational transition of poly[d(A-T)] X poly[d(A-T)].
abstract: Unique chiroptical properties of poly[d(A-T)] X poly[d(A-T)] observed in CsF solutions (Vorlícková et al., 1980) were specified by circular dichroism, ultraviolet light and 31P nuclear magnetic resonance spectroscopy. It was found that up to a 3 M concentration of the salt, caesium cations induced a gradual rearrangement of the polynucleotide double helix during which the phosphodiester bonds in one sequence changed the geometry and the base stacking decreased. At higher CsF concentrations poly[d(A-T)] X poly[d(A-T)] underwent a transition toward a novel conformation which had phosphodiester bonds in both sequences in considerably different non-B-DNA geometries.
mesh_terms: D002586:Cesium; D002942:Circular Dichroism; D005459:Fluorides; D009690:Nucleic Acid Conformation; D011067:Poly dA-dT / Q000031:analogs & derivatives; D011089:Polydeoxyribonucleotides; D013056:Spectrophotometry, Ultraviolet
chemical_list: D011089:Polydeoxyribonucleotides; D002586:Cesium; D011067:Poly dA-dT; D005459:Fluorides; C027754:cesium fluoride