title: Conformational transitions of poly(dA-dT)poly(dA-dT) in ethanolic solutions.
abstract: Examination of circular dichroic and phosphorus nuclear magnetic resonance spectra showed that poly(dA-dT)-poly(dA-dT) exhibited an ethanol-induced transition to the A form in an Na+ containing medium like natural DNAs. A mere replacement of the Na+ by Cs+ counterions meant that the polynucleotide was with a little cooperativity transformed into a novel conformation displaying a deep negative band in the long wavelength part of the CD spectrum. The presence of very low concentration of Cs2+ shifted the midpoint of the transition to a lower content of ethanol.
mesh_terms: D002942:Circular Dichroism; D000431:Ethanol; D009682:Magnetic Resonance Spectroscopy; D009690:Nucleic Acid Conformation; D011067:Poly dA-dT; D011089:Polydeoxyribonucleotides; D012996:Solutions
chemical_list: D011089:Polydeoxyribonucleotides; D012996:Solutions; D011067:Poly dA-dT; D000431:Ethanol