Structural transition of d(G4T4G4) from antiparallel to parallel G-quartet induced by divalent cations

We obtained thermodynamic parameters of an antiparallel G-quartet formation of d(G4T4G4) with 1 mM divalent cation (Mg2+, Ca2+, Mn2+, Co2+, or Zn2+). In addition, we also found that a higher concentration of a divalent cation induced a transition from an antiparallel to a parallel G-quartet structure. These results indicate that the divalent cations are a good tool for regulating the G-quartet structures and their stability.