Tsukahara S, Kim S G, Takaku H
Department of Industrial Chemistry, Chiba Institute of Technology, Japan.
Biochem Biophys Res Commun. 1993 Oct 29;196(2):990-6. doi: 10.1006/bbrc.1993.2347.
The ability of pyrimidine rich oligonucleotide phosphorothioate to form stable triple helical structures with the sequence containing the recognition site for the class II-S restriction enzyme Ksp 632-I was examined. First, we synthesized double strand oligonucleotides corresponding to the SV40 sites and studied their interaction with homopyrimidine oligodeoxyribonucleotides including replacement of the other chain either PS group (SO-ODNs) in second nucleotide position (from 5'-terminus) and end capped with the PS group at both 3'- and 5'-ends (S2O-ODNs). The resulting perfect DNA triplexes were detected by gel-mobility shift. The phosphorothioate oligonucleotide analogues (SO-ODNs) and (S2O-ODNs) were shown to inhibit enzymatic cleavage under conditions that allow for triple helix formation. Inhibition is sequence-specific and occurs in the micromolar concentration range. Of particular interest is the Sp-phosphorothioate analogue (Sp-SO-ODNs) which inhibited endonuclease more than the other phosphorothioate oligonucleotide analogues (Rp-SO-ODNs or S2O-ODNs).
研究了富含嘧啶的寡核苷酸硫代磷酸酯与含有II-S类限制性内切酶Ksp 632-I识别位点的序列形成稳定三螺旋结构的能力。首先，我们合成了与SV40位点对应的双链寡核苷酸，并研究了它们与同嘧啶寡脱氧核糖核苷酸的相互作用，包括在第二个核苷酸位置（从5'-末端起）用PS基团取代另一条链（SO-ODNs），并在3'-和5'-末端都用PS基团封端（S2O-ODNs）。通过凝胶迁移率变动检测得到了完美的DNA三链体。硫代磷酸酯寡核苷酸类似物（SO-ODNs）和（S2O-ODNs）在允许形成三螺旋的条件下显示出抑制酶切作用。抑制作用具有序列特异性，且发生在微摩尔浓度范围内。特别值得关注的是Sp-硫代磷酸酯类似物（Sp-SO-ODNs），它比其他硫代磷酸酯寡核苷酸类似物（Rp-SO-ODNs或S2O-ODNs）更能抑制内切酶。
