Kim S G, Tsukahara S, Yokoyama S, Takaku H
Department of Industrial Chemistry, Chiba Institute of Technology, Japan.
FEBS Lett. 1992 Dec 7;314(1):29-32. doi: 10.1016/0014-5793(92)81454-t.
Analogues of the homopyrimidine oligonucleotide dT15 that contained phosphorothioate bonds of a mixture of diastereoisomers or one of the two stereoisomers (either Rp or Sp) were synthesized. The analogues were mixed under conditions conducive to the formation of triple-stranded assemblies. The mixtures were characterized by their thermal stabilities (Tm values), CD spectra, and gel electrophoresis pattern. The 34-mer duplexes containing 15 central purines on one strand and 15 complementary pyrimidines on the other strand gave no detectable triple helix upon combination with dT15S14. On the other hand, 34-bp duplexes with dT15S1, having Rp or Sp, formed triple helixes. This suggests that a steric factor plays an important role in triple helix formation.
合成了含有非对映异构体混合物或两种立体异构体之一（Rp或Sp）的硫代磷酸酯键的同嘧啶寡核苷酸dT15类似物。在有利于形成三链组装体的条件下将这些类似物混合。通过它们的热稳定性（Tm值）、圆二色光谱和凝胶电泳图谱对混合物进行表征。在一条链上含有15个中心嘌呤且在另一条链上含有15个互补嘧啶的34聚体双链体与dT15S14结合时未检测到三链螺旋。另一方面，具有Rp或Sp的含dT15S1的34碱基对双链体形成了三链螺旋。这表明空间因素在三链螺旋形成中起重要作用。
