Abeydeera N Dinuka, Chow Christine S
Department of Chemistry, Wayne State University, Detroit, MI 48202, USA.
Bioorg Med Chem. 2009 Aug 15;17(16):5887-93. doi: 10.1016/j.bmc.2009.07.008. Epub 2009 Jul 9.
The synthesis of the 6-O-DPC-2-N-methylguanosine (m(2)G) nucleoside and the corresponding 5'-O-DMT-2'-O-TOM-protected 6-O-DPC-2-N-methylguanosine phosphoramidite is reported [DPC, diphenyl carbamoyl; DMT, 4,4'-dimethoxytrityl; TOM, [(triisopropylsilyl)oxy]methyl]. The availability of the phosphoramidite allows for syntheses of hairpin RNAs with site-selective incorporation of 2-N-methylguanosine modification. Four 18-nt hairpin RNA analogues representing the 970-loop region (helix 31 or h31; U960-A975) of Escherichia coli 16S rRNA were synthesized with and without modifications in the loop region. Subsequently, stabilities and conformations of the singly and doubly modified RNAs were examined and compared with the corresponding unmodified RNA. Thermodynamic parameters and circular dichroism spectra are presented for the four helix 31 RNA analogues. Surprisingly, methylations in the loop region of helix 31 slightly destabilize the hairpin, which may have subtle effects on ribosome function. The hairpin construct is suitable for future ligand-binding experiments.
报道了6 - O - 二苯基甲酰基 - 2 - N - 甲基鸟苷（m(2)G）核苷以及相应的5'- O - 二甲氧基三苯甲基 - 2'- O - 三异丙基硅基甲氧基甲基保护的6 - O - 二苯基甲酰基 - 2 - N - 甲基鸟苷亚磷酰胺的合成[DPC，二苯基甲酰基；DMT，4,4'-二甲氧基三苯甲基；TOM，[(三异丙基硅基)氧基]甲基]。该亚磷酰胺的可得性使得能够合成在特定位置选择性掺入2 - N - 甲基鸟苷修饰的发夹RNA。合成了代表大肠杆菌16S rRNA的970环区域（螺旋31或h31；U960 - A975）的四种18个核苷酸的发夹RNA类似物，其中一些在环区域进行了修饰，一些未修饰。随后，对单修饰和双修饰RNA的稳定性和构象进行了检测，并与相应的未修饰RNA进行了比较。给出了四种螺旋31 RNA类似物的热力学参数和圆二色光谱。令人惊讶的是，螺旋31环区域的甲基化会使发夹结构略微不稳定，这可能对核糖体功能有微妙影响。该发夹结构适用于未来的配体结合实验。
