Department of Chemistry & Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
Chemistry. 2013 May 27;19(22):6990-7006. doi: 10.1002/chem.201300487. Epub 2013 Apr 23.
We present the synthesis of the isobicyclo-DNA building blocks with the nucleobases A, C, G and T, as well as biophysical and biological properties of oligonucleotides derived thereof. The synthesis of the sugar part was achieved in 5 steps starting from a known intermediate of the tricyclo-DNA synthesis. Dodecamers containing single isobicyclo-thymidine incorporations, fully modified A- and T-containing sequences, and fully modified oligonucleotides containing all four bases were synthesized and characterized. Isobicyclo-DNA forms stable duplexes with natural nucleic acids with a pronounced preference for DNA over RNA as complements. The most stable duplexes, however, arise by self-pairing. Isobicyclo-DNA forms preferentially B-DNA-like duplexes with DNA and A-like duplexes with complementary RNA as determined by circular dichroism (CD) spectroscopy. Self-paired duplexes show a yet unknown structure, as judged from CD spectroscopy. Biochemical tests revealed that isobicyclo-DNA is stable in fetal bovine serum and does not elicit RNaseH activity.
我们展示了带有碱基 A、C、G 和 T 的异双环 DNA 构建块的合成，以及由此衍生的寡核苷酸的生物物理和生物学性质。糖部分的合成是从三环 DNA 合成的已知中间体开始，经过 5 步反应实现的。合成了含有单个异双环胸腺嘧啶掺入物的十二聚体、完全修饰的 A 和 T 含量序列，以及含有所有四个碱基的完全修饰的寡核苷酸，并对其进行了表征。异双环 DNA 与天然核酸形成稳定的双链体，与 RNA 互补时对 DNA 具有明显的偏好。然而，最稳定的双链体是通过自我配对形成的。异双环 DNA 通过圆二色性（CD）光谱确定，与 DNA 形成优先形成 B-DNA 样双链体，与互补 RNA 形成 A 样双链体。自我配对的双链体显示出未知的结构，这可以从 CD 光谱判断。生化测试表明，异双环 DNA 在胎牛血清中稳定，不会引发 RNaseH 活性。
