pure oligonucleotides. Oligonucleotideduplexes with parallelchainorientation were constructed incorporating dA·dT and isoGd·dC base pairs. Replacement of dC-residues by the G-clamp 3 led to extraordinarily stable duplexes (ΔTm = +11 °C for two incorporations) in ps DNA, while the pyrrolo-dC derivative 4 behaved like dC. Surprisingly, the G-clamp 3 forms an even more stable base pair with 2′-deoxyisoguanosine
合成了通过三唑接头与烷基氨基侧链束缚的新吡咯并-dC衍生物4。制备含有G-钳位3或吡咯并-dC衍生物4的寡核苷酸。在标准条件下寡核苷酸的合成和脱保护导致不需要的副产物形成。副产物被鉴定为氨基烷基侧链的丙烯腈加合物。将合成和后处理条件改变为快速脱保护化学反应并在固体支持物上进行氰基乙基的β-消除,得到纯的寡核苷酸。结合dA·dT和isoG d构建具有平行链取向的寡核苷酸双链体·dC碱基对。用G钳3取代dC残基导致ps DNA中非常稳定的双链体(两次掺入的ΔT m = +11°C),而吡咯并dC衍生物4表现得像dC。出乎意料的是,G-clamp 3与DNA中具有平行链取向的2'-脱氧异鸟苷形成了更稳定的碱基对。2'-脱氧鸟苷 在aps DNA中。