TY - JOUR
T1 - Circular Dichroism of Polynucleotides: Interactions of NiCl2 with Poly(dA-dT).Poly(dA-dT) and Poly(dG-dC).Poly(dG-dC) in a Water-in-Oil Microemulsion
AU - Airoldi, Marta
AU - Giuliani Ricci, Anna Maria
AU - Gennaro, Giuseppe
AU - Giomini, Marcello
AU - Giustini, Mauro
PY - 2008
Y1 - 2008
N2 - The thermal behavior of the synthetic, high molecular weight, double stranded polynucleotides poly(dA-dT).poly(dA-dT) [polyAT] and poly(dG-dC).poly(dGdC) [polyGC] solubilized in the aqueous core of the quaternary water-in-oil cationic microemulsion CTAB|n-pentanol|n-hexane|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 BDNA 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.
AB - The thermal behavior of the synthetic, high molecular weight, double stranded polynucleotides poly(dA-dT).poly(dA-dT) [polyAT] and poly(dG-dC).poly(dGdC) [polyGC] solubilized in the aqueous core of the quaternary water-in-oil cationic microemulsion CTAB|n-pentanol|n-hexane|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 BDNA 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.
KW - CD and UV spectroscopies
KW - model polynucleotides
KW - nickel (II) ions
KW - thermal denaturation
KW - water-in-oil microemulsions
KW - CD and UV spectroscopies
KW - model polynucleotides
KW - nickel (II) ions
KW - thermal denaturation
KW - water-in-oil microemulsions
UR - http://hdl.handle.net/10447/35826
M3 - Article
VL - 20
SP - 951
EP - 960
JO - Chirality
JF - Chirality
SN - 0899-0042
ER -