## Abstract The unwinding of DNA strands in the presence of small concentrations of Mn^2+^ ions (2 × 10^−4^−4 × 10^−4^__M__) has been studied. The process of unwinding is nonequilibrium; the DNA strands are gradually unwound at a constant temperature corresponding to the beginning of the melting cu
Interactions of metallic ions with DNA. V. DNA Renaturation Mechanism in the Presence of Cu2+
✍ Scribed by Hélène Richard; J. P. Schreiber; M. Daune
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1973
- Tongue
- English
- Weight
- 533 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Abstract
New experimental data were obtained by means of circular dichroism, melting, renaturation, and kinetic experiments, upon Cu^2+^ binding to DNA, poly dAT, and poly dGdC. They enable us to propose a model of binding giving a satisfactory explanation to all of the data found in the literature. Two types of binding sites are proposed: (a) a “sandwich” of Cu^2+^ between two adjacent G‐C pairs giving a charge‐transfer complex, and (b) a chelate between a phosphate group and a nitrogen atom of the bases (N~7~ of guanine and N~3~ of cytosine at room temperature, N~3~ of adenine after thermal opening of A‐T pair). Type (a) stabilizes the helix and keeps the two strands linked. Type (b) destabilizes the helix and explains why the kinetic rate of renaturation is the same as that of copper release.
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