Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, United States.
Ames High School, Ames, Iowa 50019, United States.
J Phys Chem B. 2024 Oct 24;128(42):10339-10347. doi: 10.1021/acs.jpcb.4c03458. Epub 2024 Oct 15.
The thermal stabilities of DNA duplexes analogous to the microRNA: mRNA complex from have been measured by free solution capillary electrophoresis. DNA duplexes with the same stems but different types of internal or bulge loops and a control with no loop have also been studied. The melting temperatures of the DNA derivatives increased linearly with the logarithm of the Na or K ion concentration in the solution. Peaks in the electropherograms corresponding to duplexes with internal or bulge loops exhibited extensive tailing at high temperatures, suggesting that denaturation occurred by slow exchange between the duplexes and their component single strands. The single strands did not separate completely from the duplexes in aqueous solutions; instead, they appeared as small subpeaks on the tails of the duplex peaks. However, complete separation of the duplexes from their component single strands was observed at 20 °C in solutions containing 300 mM tetrapropylammonium ions. In addition, counterion condensation appears to be significantly reduced in DNA duplexes containing internal or bulge loops.
通过自由溶液毛细管电泳测量了与微 RNA:mRNA 复合物类似的 DNA 双链体的热稳定性。还研究了具有相同茎但不同类型的内部或凸起环的 DNA 双链体和没有环的对照物。DNA 衍生物的熔点随溶液中 Na 或 K 离子浓度的对数线性增加。对应于具有内部或凸起环的双链体的电泳图谱中的峰在高温下表现出广泛的拖尾，表明变性是通过双链体与其组成的单链之间的缓慢交换发生的。单链在水溶液中并未完全与双链体分离；相反，它们出现在双链体峰的尾部的小亚峰上。然而，在含有 300 mM 四丙基铵离子的溶液中，在 20°C 下观察到双链体与其组成的单链完全分离。此外，在含有内部或凸起环的 DNA 双链体中，抗衡离子的凝聚似乎明显减少。
