Thermodynamics of Triple-Helix and Double-Helix Formations by Octamers of Deoxyriboadenylic and Deoxyribothymidylic Acids

  • Naoki Sugimoto
    Department of Chemistry, Faculty of Science, Konan University
  • Yuki Shintani
    Department of Chemistry, Faculty of Science, Konan University
  • Atsushi Tanaka
    Department of Chemistry, Faculty of Science, Konan University
  • Muneo Sasaki
    Department of Chemistry, Faculty of Science, Konan University

Abstract

<jats:title>Abstract</jats:title> <jats:p>The triple-helix and double-helix formations by octamers of deoxyriboadenylic and deoxyribothymidylic acids, (dA)8 and (dT)8, have been studied energetically and dynamically by UV and CD measurements, a melting analysis, curve-fitting and nearest-neighbor calculations. The UV mixing curves and CD spectra showed that the triple-helix of (dA)8·2(dT)8 mainly existed in 0.05 mol dm−3 MgCl2 buffer at a low temperature range, while the double helix of (dA)8·(dT)8 existed in 1 and 0.1 mol dm−3 NaCl buffers. The thermodynamic parameters for the triplex and duplex formations were obtained with analysis for the UV melting curves. The free-energy changes at 25 °C obtained from the melting temperature vs. oligomer concentration plots in the MgCl2 buffer were −20.7 kJ mol−1 for the triplex formation and −27.3 kJ mol−1 for the duplex formation, respectively, which were consistent with the values obtained from the curve-fitting calculations. The free-energy changes for the duplex formation at 25 °C were −28.5 kJ mol−1 in 1 mol dm−3 NaCl buffer, and −11.6 kJ mol−1 in 0.1 mol dm−3 NaCl bufer, respectively. These values were discussed in comparison with the predicted values by the nearest-neighbor calculation.</jats:p>

Journal

References(17)*help

See more

Details 詳細情報について

Report a problem

Back to top