title: Spectroscopic studies of conformational transitions in double stranded DNAs in the presence of carcinogenic nickel compounds and an antitumoral drug (SOAZ).
abstract: The influence of an antitumoral drug, the pentaziridinocyclodiphosphatiazene (SOAZ), on the right----left-handed helix conformational transition of Poly (dG-dC). Poly (dG-dC) induced by carcinogenic or mutagenic Nickel compounds has been studied by ultraviolet absorbance and circular dichroïsm measurements. The B----Z transition of the polynucleotide is induced in two steps, in a similar way whatever the origin of the Nickel ions (NiCl2, NiSO4, Ni3S2, NiCO3). The midpoint of the second step (right----left-transition) is located around 0.4 mM Ni2+. The addition of SOAZ to the Poly (dG-dC). Poly (dG-dC) modifies this transition which is shifted to 2 mM Ni2+ for a 1 SOAZ/10 DNA phosphates ratio. The right-handed helix is stabilized and for a 1.5 SOAZ/phosphate ratio no B----Z transition is observed even for a tenfold amount of added Nickel (4 mM Ni2+). The addition of SOAZ to the DNA initially converted to a Z conformation by the presence of Nickel inhibits the return to the B form.
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D001389:Azirines / Q000494:pharmacology*; D002273:Carcinogens; D002942:Circular Dichroism; D004247:DNA; D009532:Nickel / Q000633:toxicity*; D009690:Nucleic Acid Conformation; D011089:Polydeoxyribonucleotides; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000970:Antineoplastic Agents; D001389:Azirines; D002273:Carcinogens; D011089:Polydeoxyribonucleotides; C019530:poly(dC-dG); C035161:pentazirinocyclodiphosphathiazene; D009532:Nickel; D004247:DNA