Strand breaks in plasmid DNA following positional changes of Auger-electron-emitting radionuclides.
The purpose of our studies is to elucidate the kinetics of DNA strand breaks caused by low-energy Auger electron emitters in close proximity to DNA. Previously we have studied the DNA break yields in plasmids after the decay of indium-111 bound to DNA or free in solution. In this work, we compare the DNA break yields in supercoiled DNA of iodine-125 decaying close to DNA following DNA intercalation, minor-groove binding, or surface binding, and at a distance from DNA. Supercoiled DNA, stored at 4 degrees C to accumulate radiation dose from the decay of 125I, was then resolved by gel electrophoresis into supercoiled, nicked circular, and linear forms, representing undamaged DNA, single-strand breaks, and double-strand breaks respectively. DNA-intercalated or groove-bound 125I is more effective than surface-bound radionuclide or 125I free in solution. The hydroxyl radical scavenger DMSO protects against damage by 125I free in solution but has minimal effect on damage by groove-bound 125I.
Adelstein
S J
SJ
Harvard Medical School, Department of Radiology, Boston, MA, USA.
Kassis
A I
AI
D004249:DNA Damage; D004278:DNA, Superhelical / Q000378:metabolism / Q000528:radiation effects*; D007205:Indium Radioisotopes / Q000378:metabolism; D007457:Iodine Radioisotopes / Q000378:metabolism; D018499:Linear Energy Transfer; D010957:Plasmids / Q000235:genetics / Q000528:radiation effects*
D004278:DNA, Superhelical; D007205:Indium Radioisotopes; D007457:Iodine Radioisotopes