23Na NMR study of DNA thermal transconformation in presence of cysteamine radioprotector |
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Authors: | J Lematre G Mallet D Vasilescu |
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Institution: | University of Nice, Biophysics Laboratory, Parc Valrose, France. |
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Abstract: | DNA thermal transconformation is studied in absence and in presence of the cysteamine radioprotector, by observing the delta nu 1/2 variation of 23Na NMR peaks. The sodium state (Free or Bound) is discussed with the help of a two states model with RF and RB relaxation rates. The delta nu 1/2 behaviour during the DNA transconformation shows clearly the electrostatic interaction with cysteamine which is accompanied by an Na+ ejection out of phosphate sites. The temperature dependence of delta nu 1/2 in all cases leads to the conclusion that RBc (the average relaxation rate of sodium nuclei that remain bound in the coil state of DNA) tends to zero. |
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