Parallel stranded DNA with AT base pairing |
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Authors: | A K Shchyolkina Il'ichova" target="_blank">I A Lysov YuPIl'ichova A A Chernyi Chernov" target="_blank">B K Golova YuBChernov B P Gottikh V L Florentiev |
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Institution: | V. A. Engelhardt Institute of Molecular Biology, USSR Academy of Sciences, Moscow. |
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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. |
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