A Thermodynamic Investigation into the Stabilization of Poly(dA)¡¤[poly(dT)]2 Triple Helical DNA by Various Divalent Metal Ions

Bulletin of the Korean chemical society

Ga Young Yeo¹  Jinah Jung¹  Tae Sub Cho¹  Bae Wook Lee¹  Byung Hoon Choi¹  Sung Wook Han¹ 

关键词: Triplex DNA;    Divalent ions;    Thermodynamics;    Enthalpy;    Entropy;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

Effects of representative group II and transition metal ions on the stability of the poly(dA)·[poly(dT)]₂ triplex were investigated by the van’t Hoff plot constructed from a thermal melting curve. The transition, poly(dA)·[poly(dT)]₂ �? poly(dA)·poly(dT) + poly(dT), was non-spontaneous with a positive Gibb’s free energy, endothermic (ツHo > 0), and had a favorable entropy change (ツSo > 0), as seen from the negative slope and positive y-intercept in the van’t Hoff plot. Therefore, the transition is driven by entropy change. The Mg²⁺ ion was the most effective at stabilization of the triplex, with the effect decreasing in the order of Mg²⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺. A similar stabilization effect was found for the duplex to single strand transition: poly(dA)·poly(dT) + poly(dT) �? poly(dA) + 2poly(dT), with a larger positive free energy. The transition metal ions, namely Ni²⁺, Cu²⁺, and Zn²⁺, did not exhibit any effect on triplex stabilization, while showing little effect on duplex stabilization. The different effects on triplex stabilization between group II metal ions and the transition metal ions may be attributed to their difference in binding to DNA; transition metals are known to coordinate with DNA components, including phosphate groups, while group II metal ions conceivably bind DNA via electrostatic interactions. The Cd²⁺ ion was an exception, effectively stabilizing the triplex and melting temperature of the third strand dissociation was higher than that observed in the presence of Mg2+, even though it is in the same group with Zn²⁺. The detailed behavior of the Cd²⁺ ion is currently under investigation.

【 授权许可】

Unknown