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Circular dichroism of polynucleotides: Interactions of NiCl 2 with poly(dA‐dT)·poly(dA‐dT) and poly(dG‐dC)·poly(dG‐dC) in a water‐in‐oil microemulsion
Author(s) -
Airoldi Marta,
Gennaro Giuseppe,
Giomini Marcello,
Giuliani Anna Maria,
Giustini Mauro
Publication year - 2008
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20531
Subject(s) - polynucleotide , chemistry , circular dichroism , ionic strength , microemulsion , ionic bonding , cationic polymerization , denaturation (fissile materials) , aqueous solution , crystallography , analytical chemistry (journal) , nuclear chemistry , polymer chemistry , organic chemistry , pulmonary surfactant , biochemistry , ion
The thermal behavior of the synthetic, high molecular weight, double stranded polynucleotides poly(dA‐dT)·poly(dA‐dT) [polyAT] and poly(dG‐dC)·poly(dG‐dC) [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 NiCl 2 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. Chirality, 2008. © 2008 Wiley‐Liss, Inc.