title: Binding of Mg2+, Cd2+, and Ni2+ to liquid crystalline NaDNA: polarized light microscopy and NMR investigations.
abstract: The interaction of the divalent metal ions Mg(2+), Cd(2+), and Ni(2+) with liquid crystalline NaDNA solutions (molar ratios Me(2+)/DNA-phosphate </=0.050) was investigated by polarized light microscopy and multinuclear (31)P, (2)H, and (23)Na NMR. Our findings show that the state of the cholesteric NaDNA phase at equal MgCl(2), CdCl(2), or NiCl(2) concentration is affected in a different way and to a different extent by the nature of the divalent cation. Indeed, we found that the occurrence of an isotropic phase is markedly favored by Mg(2+), and to a lower extent by Cd(2+), and that the pitch of the cholesteric phase decreases in the presence of Cd(2+) or Ni(2+). (23)Na NMR spectroscopy also shows differences between the binding behavior of Mg(2+) and the transition metal ions in the counterion atmosphere around DNA. The results are discussed in terms of different binding modes of the metal ions.
authors.affiliation: Dipartimento di Scienze Chimiche, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.S. 554, 09042 Monserrato, Cagliari, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Catte
authors.forename: Flaminia
authors.initials: F
authors.lastname: Cesare-Marincola
authors.forename: Johan R C
authors.initials: JR
authors.lastname: van der Maarel
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Saba
authors.forename: Adolfo
authors.initials: A
authors.lastname: Lai
mesh_terms: D002104:Cadmium / Q000737:chemistry*; D003460:Crystallization; D004247:DNA / Q000032:analysis / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008859:Microscopy, Polarization / Q000379:methods; D009532:Nickel / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry*
chemical_list: D002104:Cadmium; D009532:Nickel; D004247:DNA; D012964:Sodium; D008274:Magnesium