Reversed Cation Selectivity of G8 -Octamer and G16 -Hexadecamer towards Monovalent and Divalent Cations
Ying He1, Yanbin Zhang2, Lukasz Wojtas1
1Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, Tampa, Florida, 33620, United States.
Abstract:
A reverse-binding-selectivity between monovalent and divalent cations was observed for two different self-assembly G16 -hexadecamer and G8 -octamer systems. The dissociation constant between G4 -quadruplex and monomer was calculated via VT-1 H NMR experiments. Quantitative energy profiles revealed entropy as the key factor for the weaker binding toward Ba2+ compared with K+ in the G8 -octamer system despite stronger ion-dipole interactions. This study is the first direct comparison of the G4 -quartet binding affinity between mono and divalent cations and will benefit future applications of G-quadruplex-related research. Further competition experiments between the G8 -octamer and 18-crown-6 with K+ demonstrated the potential of this G8 system as a new potassium receptor.
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