Conversion of Covalently Closed Circular DNA into Circular and Linear DNA by Ionizing Radiation in the Presence and Absence of DNA-binding or Intercalating Drugs
It is generally accepted that hydroxyl radicals produced by the action of ionizing radiation in dilute aqueous solutions are predominantly responsible for the induction of strand breaks in DNA. It is also known that Tris buffer and citrate buffer can act as OH-scavengers. Nevertheless, Tris is still used as a solvent for DNA in irradiation experiments, even very recently, as can be seen from the work of McCormack et al. and Belli, reported during this meeting. We therefore considered it appropriate to study the OH-scavenging capacity of different buffers by measuring the DNA strand break production after ionizing radiation, starting with Tris buffer and phosphate buffer. Furthermore, we wanted to know whether drugs, known to interact with the DNA molecule, affect the radiation induced degradation and whether there is any correlation to the binding properties. Such knowledge might be important for the formulation of safety standards.
KeywordsTris Buffer Strand Break Drug Molecule Scavenge Capacity Strand Breakage
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