Structural switch of telomere DNA by pH and monovalent cation.

Because of the importance of telomere DNAs, the structures of these DNAs in vivo and in vitro are currently of great research interest in the medical, pharmaceutical, chemical, and industrial fields. In this study, we investigated the structure and thermodynamic properties of the telomere DNAs in the presence of monovalent cations, K+ or Na+. The results demonstrate that the duplex-quadruplex conversion of the 1:1 mixture of telomere G-rich and C-rich sequences can be induced depending on cation species and its concentration. Furthermore, slightly acidic condition stabilizes the i-motif and forces the mixture to dissociate. These results suggest that the structure and stability of telomere DNAs can be controlled by monovalent cation and pH.