Circular dichroism of polyncleotides: Interactions of NiCl2 with poly(dA-dT)center dot poly(dA-dT) and poly(dG-dC)center dot poly(dG-dC) in a water-in-oil microemulsion

Research Area: Uncategorized Year: 2008
Type of Publication: Article
  • Marta Airoldi
  • Giuseppe Gennaro
  • Marcello Giomini
  • Anna Maria Giuliani
  • Mauro Giustini
Journal: CHIRALITY Volume: 20
Number: 9, SI Pages: 951-960
Month: October
ISSN: 0899-0042
11th International Conference on Circular Dichroism, Groningen, NETHERLANDS, SEP 02-06, 2007
The thermal behavior of the synthetic, high molecular weight, double stranded polynucleotides poly(dA-dT)center dot poly(dA-dT) [polyAT] and poly(dG-dC)center dot poly(dG-dC) [polyGC] solubilized in the aqueous core of the quaternary water-in-oil cationic microemulsion CTAB vertical bar n-pentanol vertical bar n-hexane vertical bar water in the presence of increasing amounts of NiCl2 at several constant ionic strength values (NaCl) has been studied by means of circular dichroism and electronic absorption spectroscopies. In the microemulsive medium, both polynucleotides show temperature-induced modifications that markedly vary with both Ni(II) concentration and ionic strength. An increase of temperature causes denaturation of the polyAT duplex at low nickel concentrations, while more complex CD spectral modifications are observed at higher nickel concentrations and ionic strengths. By contrast, thermal denaturation is never observed for polyGC. At low Ni(II) concentrations, the increase of temperature induces conformational transitions from B-DNA to Z-DNA form, or, more precisely, to left-handed helical structures. In some cases, at higher nickel concentrations, the CD spectra suggest the presence of Z `-type forms of the polynucleotide.
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