title: Parallel stranded DNA with AT base pairing.
abstract: The concentration and temperature dependences of the UV and CD spectra of the oligonucleotide 3'-d(ApTpApTpApTpApTpApTp)-O(CH2)6O-5'-d(pApTpApTpApTpApT pApT) (eicosamer) in aqueous solution at pH 7 in the presence of 0.5 M NaCl were studied. At less than 10(-6) M, the eicosamer was shown to form in solution a hairpin with parallel orientation of chains (parallel hairpin). From thermal denaturation profiles [A260(T)] the thermodynamic parameters, delta H degrees, delta S degrees and Tm for parallel hairpin formation were calculated to be -90 +/- 8 kJ/mol. -300 +/- 20 J.mol-1.K-1 and 40.5 degrees C, respectively. The CD spectra of the parallel double helix differed from those of B-form DNA and had characteristic features: decreasing magnitude of the positive maximum at 265 nm and a negative peak at 285 nm.
authors.affiliation: V. A. Engelhardt Institute of Molecular Biology, USSR Academy of Sciences, Moscow.
authors.forename: A K
authors.initials: AK
authors.lastname: Shchyolkina
authors.lastname: Lysov YuP
authors.forename: I A
authors.initials: IA
authors.lastname: Il'ichova
authors.forename: A A
authors.initials: AA
authors.lastname: Chernyi
authors.lastname: Golova YuB
authors.forename: B K
authors.initials: BK
authors.lastname: Chernov
authors.forename: B P
authors.initials: BP
authors.lastname: Gottikh
authors.forename: V L
authors.initials: VL
authors.lastname: Florentiev
mesh_terms: D000225:Adenine; D001482:Base Composition; D001483:Base Sequence; D002942:Circular Dichroism; D004247:DNA; D006358:Hot Temperature; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics; D013941:Thymine
chemical_list: D004247:DNA; D000225:Adenine; D013941:Thymine