Effect of divalent cations on antiparallel G-quartet structure of d(G(4)T(4)C(4))

The thermodynamic parameters of an antiparallel G-quartet formation of d(G( 4)T(4)G(4)) with 1 mM divalent cation (Mg2+, Ca2+, Mn2+, Co2+, and Zn2+) we re obtained. The thermodynamic parameters showed that the divalent cation d estabilizes the antiparallel G-quartet of d(G(4)T(4)G(4)) in the Following order: Zn2+ > Co2+ > Mn2+ > Mg2+ > Ca2+. In addition, a higher concentratio n of a divalent cation induced a transition from an antiparattel to a paral lel G-quartet structure. These results indicate that these divalent cations are a good tool for regulating the G-quartet structures. (C) 2001 Publishe d by Elsevier Science B.V. on behalf of the Federation of European Biochemi cal Societies.