Sabahi A, Guidry J, Inamati G B, Manoharan M, Wittung-Stafshede P
Department of Chemistry, Tulane University, 6823 St Charles Avenue, New Orleans, LA 70118-5698, USA.
Nucleic Acids Res. 2001 May 15;29(10):2163-70. doi: 10.1093/nar/29.10.2163.
In this study, we characterize the thermodynamics of hybridization, binding kinetics and conformations of four ribose-modified (2'-fluoro, 2'-O-propyl, 2'-O-methoxyethyl and 2'-O-aminopropyl) decameric mixed-sequence oligonucleotides. Hybridization to the complementary non-modified DNA or RNA decamer was probed by fluorescence and circular-dichroism spectroscopy and compared to the same duplex formed between two non-modified strands. The thermal melting points of DNA-DNA duplexes were increased by 1.8, 2.2, 0.3 and 1.3 degrees C for each propyl, methoxyethyl, aminopropyl and fluoro modification, respectively. In the case of DNA-RNA duplexes, the melting points were increased by 3.1, 4.1 and 1.0 degrees C for each propyl, methoxyethyl and aminopropyl modification, respectively. The high stability of the duplexes formed with propyl-, methoxyethyl- and fluoro-modified oligonucleotides correlated with high preorganization in these single-strands. Despite higher thermodynamic duplex stability, hybridization kinetics to complementary DNA or RNA was slower for propyl- and methoxyethyl-modified oligonucleotides than for the non-modified control. In contrast, the positively-charged aminopropyl-modified oligonucleotide showed rapid binding to the complementary DNA or RNA.
在本研究中，我们表征了四种核糖修饰的（2'-氟、2'-O-丙基、2'-O-甲氧基乙基和2'-O-氨丙基）十聚体混合序列寡核苷酸的杂交热力学、结合动力学和构象。通过荧光和圆二色光谱法探测与互补的未修饰DNA或RNA十聚体的杂交情况，并与两条未修饰链之间形成的相同双链体进行比较。对于DNA-DNA双链体，每种丙基、甲氧基乙基、氨丙基和氟修饰分别使热熔点提高了1.8、2.2、0.3和1.3摄氏度。对于DNA-RNA双链体，每种丙基、甲氧基乙基和氨丙基修饰分别使熔点提高了3.1、4.1和1.0摄氏度。由丙基、甲氧基乙基和氟修饰的寡核苷酸形成的双链体的高稳定性与这些单链中的高预组织性相关。尽管双链体具有更高的热力学稳定性，但丙基和甲氧基乙基修饰的寡核苷酸与互补DNA或RNA的杂交动力学比未修饰对照慢。相比之下，带正电荷的氨丙基修饰的寡核苷酸与互补DNA或RNA显示出快速结合。
