title: Reconstitution of intercalator-induced DNA scission by an active component from nuclear extracts.
abstract: Treatment with intercalating agents causes formation of protein-associated DNA breaks in mammalian cells in culture and in the nuclei isolated from these cells. We found that this effect, when induced by the intercalator m-AMSA, required a component which could be dissociated from nuclei by 0.3 M NaCl. The effect was restored by combining the extracted nuclei with the nuclear extract. The active component of the extract eluted in gel filtration at a point corresponding to a molecular weight of 800 000. During its reaction with DNA, DNA-protein links and DNA breaks appeared in approximately equal frequencies. In this respect the reaction stimulated by m-AMSA resembled the reaction of a topoisomerase with DNA. However, intercalator-stimulated formation of protein-associated DNA breaks differed from the activity of the nuclear topoisomerase I in that there was a different optimum salt concentration and a different apparent molecular weight.
mesh_terms: D000609:Aminoacridines / Q000494:pharmacology*; D000677:Amsacrine; D000818:Animals; D002250:Carbon Radioisotopes; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000378:metabolism* / Q000528:radiation effects; D007364:Intercalating Agents / Q000494:pharmacology*; D007700:Kinetics; D007939:Leukemia L1210 / Q000378:metabolism; D051379:Mice
chemical_list: D000609:Aminoacridines; D002250:Carbon Radioisotopes; D004273:DNA, Neoplasm; D007364:Intercalating Agents; D000677:Amsacrine