Synthesis and thermal denaturation studies of novel 2′-O,3′-C-linked bicyclic oligonucleotides with a methoxy or a piperazino group facing the major groove of nucleic acid duplexes
作者:Michael Raunkjær、Mads D. Sørensen、Jesper Wengel
DOI:10.1039/b414454f
日期:——
With the aim of evaluating duplex stabilities of oligonucleotides (ONs) with major groove facing functionalities, two novel 2â²-O,3â²-C-linked bicyclic nucleoside phosphoramidite building blocks were synthesized by routes involving regioselective O-methylation or piperazine attachment using carbonyldiimidazole coupling chemistry. The novel monomers were incorporated into 9-mer mixed base ONs and the thermal stability toward complementary single stranded DNA and RNA was evaluated by thermal denaturation experiments. O-methylated ONs confirmed the applicability of the functionalized bicylic sugar unit for attachment of groups facing the major groove and satisfactory binding properties towards the RNA complement were observed. For the piperazino modified ONs, experiments were performed in aqueous buffers with low (40 mM) and medium (110 mM) salt concentrations, at pH 5 and pH 7. A change from a medium to a low salt concentration induced a significant relative increase in the thermal stability of modified duplexes toward both DNA and RNA complements, which suggests protonation of the piperazino group under the experimental conditions applied.
为了评估具有主沟槽朝向功能的寡核苷酸(ON)的双链稳定性,我们使用羰基二咪唑偶联化学方法,通过涉及区域选择性O-甲基化或哌嗪连接的途径,合成了两种新型2â²-O,3â²-C-连接的双环核苷磷酸酰胺构建模块。将新型单体掺入9-mer混合碱基ON中,并通过热变性实验评估其对互补单链DNA和RNA的热稳定性。O-甲基化ON证实了功能化双环糖单元在朝向主沟槽的基团连接方面的适用性,并观察到其对RNA互补物的结合性能令人满意。对于哌嗪修饰的ON,在pH 5和pH 7下,在低盐浓度(40 mM)和中盐浓度(110 mM)的水缓冲液中进行实验。从中等盐浓度到低盐浓度的变化导致修饰的双链对DNA和RNA互补物的热稳定性显着相对增加,这表明在所应用的实验条件下,哌嗪基团发生了质子化。