Gk. Kuipers et Mvm. Lafleur, CHARACTERIZATION OF DNA-DAMAGE INDUCED BY GAMMA-RADIATION-DERIVED WATER RADICALS, USING DNA-REPAIR ENZYMES, International journal of radiation biology (Print), 74(4), 1998, pp. 511-519
Citations number
31
Categorie Soggetti
Radiology,Nuclear Medicine & Medical Imaging","Biology Miscellaneous","Nuclear Sciences & Tecnology
Purpose: To characterize the DNA damage profiles due to gamma-radiatio
n induced water radicals. Materials and methods: Double stranded (ds)
Phi X174 DNA was irradiated in aqueous solution with gamma-rays under
different gassing conditions (O-2, N2O or N-2) and the damage profiles
were determined using DNA repair enzymes. Results: The DNA damage pro
file under O-2 is characterized by about equal numbers of direct singl
e-strand breaks (ssb) and Fpg sensitive sites, whereas endonuclease II
I and exonuclease III sites are formed in lower amounts. The DNA damag
e profiles under N2O and N-2 in phosphate buffer consist predominantly
of direct single-strand breaks. Fpg sensitive sites dominate the DNA
damage profile under N-2 in phosphate buffer in the presence of the ra
dical scavenger 2-methyl propan-2-ol, where (almost) only . H atoms ar
e present. Conclusions: Both . OH radicals and . H atoms induce direct
single-strand breaks, but . OH radicals are the most effective ones.
Fpg sensitive sites are induced in high amounts by both OH radicals an
d . H atoms, but when both types of radicals are present, the formatio
n of Fpg sensitive sites is prevented. Hydrated electrons (e(aq)(-)) c
ontribute to inactivation of DNA, although only a very small fraction
of the e(aq)(-) is involved in this process.