Molecular study of thiol-mediated DNA radioprotection

We compare the effect of four ligands on the radiolysis of a plasmid DNA with fast neutrons. Three aminothiols, WR-1065, WR-151326 and cysteamine are studied and compared to the putrescine. We show the influence of the charge and the chemical structure of the ligand on their radioprotective ability. The putrescine, which acts only as a OH. scavenger, is less protective than the three thiols, since their SH function is involved in the ''chemical repair'' of the DNA damages. Among these thiols, the cysteamine is less protective than WR-1065, which is less efficient than WR-151326. The protection of a 80 base pairs DNA fragment by the molecules with Z=+2 is sequence-modulated and varies with the ligand and its concentration.