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Interactions of metallic ions with DNA. V. DNA Renaturation Mechanism in the Presence of Cu 2+
Author(s) -
Richard Hélène,
Schreiber J. P.,
Daune M.
Publication year - 1973
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1973.360120102
Subject(s) - chemistry , guanine , crystallography , circular dichroism , dna , helix (gastropod) , metal , cytosine , kinetic energy , copper , stereochemistry , polynucleotide , nucleotide , biochemistry , organic chemistry , ecology , physics , quantum mechanics , biology , snail , gene
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.