title: Alteration of the cytoplasmic endonuclease cleavage pattern of SV-40 deoxyribonucleic acid in the presence of ATP, actinomycin D and ethidium bromide.
abstract: Endonuclease activities of cytoplasmic extracts of BSC-1 (E1) and BHK-21-cl 13 (E2) cells were assayed with SV-40 as a substrate and analysed by velocity sedimentation in alkaline and neutral sucrose gradients. Endonucleases were found to require Mg2+ ions for their activity. E1 endonuclease generated linear 6 S DNA fragments, pointing to non-random double-strand cleavage of DNA ; the action of E2 endonuclease resulted in double-strand DNA cleavage to fragments heterogeneous in size. Both endonucleases were inhibited by ATP. The inhibitory effect of actinomycin D (AD) was proportional to the AD/DNA molar ratio. AD+ATP association as well as the presence of ethidium bromide altered the cleavage pattern of E1 towards the predominance of single-strand breaks.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000201:enzymology; D004279:DNA, Viral; D003609:Dactinomycin / Q000494:pharmacology*; D004720:Endonucleases; D004996:Ethidium / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology; D013539:Simian virus 40; D014776:Virus Cultivation
chemical_list: D004279:DNA, Viral; D003609:Dactinomycin; D000255:Adenosine Triphosphate; D004720:Endonucleases; D004996:Ethidium; D008274:Magnesium