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Effects of calcium and manganese ions on the helix–coil transition of DNA
Author(s) -
Blagoi Yu. P.,
Sorokin V. A.,
Valeev V. A.,
Gladchenko G. O.
Publication year - 1983
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.360220704
Subject(s) - chemistry , ion , bivalent (engine) , manganese , crystallography , dna , calcium , nucleic acid denaturation , denaturation (fissile materials) , analytical chemistry (journal) , inorganic chemistry , nuclear chemistry , chromatography , biochemistry , organic chemistry , metal , base sequence
The thermal denaturation method was employed to study the effect of Ca 2+ and Mn 2+ ions on the DNA helix–coil transition parameters at Na + concentrations of 10 −3 –10 −1 M . At 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 Mn 2+ and Ca 2+ 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 Mn 2+ concentrations, at which the above effects occur, are an order of magnitude lower than the Ca 2+ concentrations. Comparison of experimental results and calculation in terms of the ligand theory permitted estimation of binding constants characterizing association between Mn 2+ and Ca 2+ 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.