Kassis A I, Harapanhalli R S, Adelstein S J
Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Radiat Res. 1999 Feb;151(2):167-76.
To elucidate the kinetics of the induction of DNA strand breaks by low-energy Auger electron emitters, we compared the yields of DNA breaks in supercoiled pUC19 DNA after the decay of 125I (1) in proximity to DNA after minor-groove binding (125I-iodoHoechst 33342, 125IH) and (2) at a distance from DNA (125I-iodoantipyrine, 125IAP). Iodine-125 bound to the minor groove in DNA or free in solution is equally effective per decay in producing single-strand breaks (SSBs), while 125I bound to the minor groove is 6.7-fold more efficient than 125I free in solution in producing double-strand breaks (DSBs) (1.08 +/- 0.13 compared to 0.16 +/- 0.01 DSB/decay). Consequently, SSB to DSB ratios for 125IAP and gamma radiation (20.7 +/- 2.9 and 43.8 +/- 1.5, respectively) are greater than that for 125IH (2.9 +/- 0.4). Finally, the decay of 125IH leads to fragmentation of plasmid DNA beyond SSBs and DSBs.
为了阐明低能俄歇电子发射体诱导DNA链断裂的动力学，我们比较了在小沟结合后（125I-碘化赫斯特33342, 125IH）125I (1) 在靠近DNA处衰变后以及(2) 在远离DNA处（125I-碘安替比林, 125IAP）超螺旋pUC19 DNA中DNA断裂的产率。与DNA小沟结合的或游离于溶液中的125I在每次衰变产生单链断裂（SSB）方面同样有效，而与小沟结合的125I在产生双链断裂（DSB）方面比游离于溶液中的125I效率高6.7倍（分别为1.08±0.13与0.16±0.01 DSB/衰变）。因此，125IAP和γ辐射的SSB与DSB比率（分别为20.7±2.9和43.8±1.5）大于125IH的比率（2.9±0.4）。最后，125IH的衰变导致质粒DNA断裂超过单链断裂和双链断裂。
