title: Binding of ethidium and bis(methidium)spermine to Z DNA by intercalation.
abstract: The interaction of ethidium bromide, a DNA intercalating drug, and bis( methidium )spermine, a DNA bis-intercalating compound, with the left-handed Z form of poly(dG-dC) has been studied in 4.4 M NaCl. Spectrophotometric analysis using absorption, fluorescence and circular dichroism indicates that the complex formed between ethidium and Z DNA resembles very closely that formed with B DNA. This suggests that ethidium binds to Z DNA by intercalation. 31P NMR spectra are presented showing both the conversion of the Z form to the B form with increasing amounts of drug and the typical Z form spectrum at low binding densities. Data are also presented which show that the bifunctional intercalator bis( methidium )spermine binds to Z DNA in a manner similar to its binding to B DNA, i.e., by bis-intercalation. These results are important for our understanding the behavior of Z DNA and its biological significance.
mesh_terms: D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D004247:DNA; D004996:Ethidium / Q000031:analogs & derivatives*; D007364:Intercalating Agents; D009682:Magnetic Resonance Spectroscopy; D009690:Nucleic Acid Conformation; D011089:Polydeoxyribonucleotides; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013950:Thymus Gland
chemical_list: D007364:Intercalating Agents; D011089:Polydeoxyribonucleotides; C019530:poly(dC-dG); C037704:bismethidium spermine; D004247:DNA; D004996:Ethidium