Acyclic, achiral enamide nucleoside analogues. The importance of the CC bond in the analogue for its ability to mimic natural nucleosides
作者:Asger B. Petersen、Michael Å. Petersen、Ulla Henriksen、Steen Hammerum、Otto Dahl
DOI:10.1039/b307394g
日期:——
The conformations of an acyclic, achiral enamide thymidine analogue 1 have been studied by model building and geometry calculations, as well as by NMR NOE and UV experiments. The results indicate that there are no significant barriers to rotation around any of the σ bonds, in particular the N1–C1′ enamide bond, and that the analogue should be able to accommodate conformations that mimic the conformations of natural nucleosides in A- and B-type helices quite well. For comparison the saturated analogue 2 has been prepared and built into oligonucleotides. It is shown that incorporation of 2 in oligonucleotides results in a much larger depression of the melting temperature (ΔTm
−10 to −12.5 °C) than does incorporation of 1
(ΔTm
−5 to −6.5 °C).
通过对模型构建、几何计算以及NMR NOE和UV实验的研究,探讨了无环非手性酰胺胸苷类似物1的构象。结果表明,围绕任何σ键,特别是N1-C1'酰胺键的旋转不存在显著的能垒,且该类似物应能很好地适应A型和B型螺旋中天然核苷的构象。为了对比,制备并构建了饱和类似物2到寡核苷酸中。结果显示,将2引入寡核苷酸中会导致熔点温度大幅下降(ΔTm −10至−12.5°C),而引入1则较小(ΔTm −5至−6.5°C)。