Effects of calcium and manganese ions on the helix–coil transition of DNA

✍ Scribed by Yu. P. Blagoi; V. A. Sorokin; V. A. Valeev; G. O. Gladchenko

• Publisher: Wiley (John Wiley & Sons)
• Year: 1983
• Tongue: English
• Weight: 906 KB
• Volume: 22
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360220704

✦ Synopsis

Synopsis

The thermal denaturation method was employed to study the effect of Ca2+ and Mn2+ ions on the DNA helix-coil transition parameters at Na+ concentrations of 10-3-10-1M. A t low ion concentrations, thermal stability increases, the melting range passes through a maximum, and the denaturation curves become asymmetric. These changes are quantitatively similar for Mn2+ and Ca2+ ions. With a further increase in the concentration of bivalent ions, the conformational transition temperatures pass through a maximum, and the melting range first tends to saturation and then rapidly decreases to 1-2°C. The Mn2+ concentrations, at which the above effects occur, are an order of magnitude lower than the Ca2+ concentrations.

Comparison of experimental results and calculation in terms of the ligand theory permitted estimation of binding constants characterizing association between Mn2+ and Ca2+ ions and bases of native and denatured DNA. We show that, unlike the interaction with phosphates, bivalent ion-DNA base binding is weakly dependent on monovalent ion concentration in the solution.