Studies on stereoregulated phosphorothioates for their gene-regulatory ability

在反义技术中，最有前途的诊断方法之一，严重的病毒性疾病，。已经专门研究了具有硫代磷酸酯键的硫代磷酸酯寡脱氧核苷酸（S-寡核苷酸）。然而，为了将这种方法应用于临床，一直存在一个关键的未解决的问题，即人们应该在由每个硫代磷酸酯键的立体异构产生的许多立体异构的S-寡核苷酸中鉴定和制备真正有效的特定结构，因此，在本研究中，我们进行了以下研究以克服上述问题。(1)我们用2D-NMR分析结合分子动力学计算研究了硫代磷酸酯的Rp和Sp构型与S-oligo RNA/DNA双链体结构之间的关系。已阐明，与RNA的双链体的结构彼此相似，并且与野生型DNA-RNA双链体的结构相似，尽管Rp连接产生更高的Tm，这表明与野生型DNA-RNA双链体的结构相似。 关于我们 双链体稳定性取决于除双链体结构以外的因素，可能是水合程度。另一方面，双链体结构的差异被认为是负责S-oligo-DNA杂交稳定性。这些新的发现表明，适当的配置取决于目标，这一规则的机制也取决于它。还研究了S-oligo polyC的非特异性抗病毒活性，发现这是由于其独特的四链溶液结构，i-基序，其稳定性取决于其Rp或Sp构型。此外，一个可能的目标基因的S-寡聚C，端粒C-重复，已被调查的结构方面，它已被发现，有异构的C重复四分体。这一新发现不仅有助于理解S-oligo非特异性活性的整个机制，而且有助于理解端粒拓扑结构与癌症和衰老相关的生物学功能。(3)研究了另一个尚未解决的重要课题S-寡聚物的立体选择性合成，发现在亚磷酸酯法中使用间氯甲酚作为离去基团导致在碱性条件下的高立体选择性和高酯交换产率。少

In the antisense technique, one of the most promising diagnostic methods for severe viral diseases, . phosphorothioate oligodeoxynucleotides (S-oligos) which has a thiophosphate linkage have been investigated exclusively. To apply this method in clinic, however, there has been a crucial unsolved problem that one should identify and prepare the truly effective specific structure among numbers of stereoisomeric S-oligos arising from the stereoisomerism of each thiophosphate linkage, and in the present study, therefore, we have performed following investigation s to overcome the above problem. (1) We have carried out 2D-NMR analysis combined with molecular dynamic calculation on the relationship between the thiophosphate Rp and Sp configurations and the S-oligo RNA/DNA duplex structure. It has been elucidated that the structure of the duplexes with RNA is similar with each other as well as with that of wild type DNA-RNA duplex, although Rp linkage produced higher Tm, indicative that the d … More uplex stability is dependent such a factor other than the duplex structure, possibly as extent of hydration. On the other hand, difference of the duplex structure was found to be responsible for S-oligo-DNA hybrid stability. These new findings indicate that the, suitable configuration depends on the target, and that the mechanism of this rule also on it. (2). Nonspecific antiviral activity of S-oligo polyC has also been studied, and found to be due to its unique four-stranded solution structure, i-motif, whose stability is dependent on its Rp or Sp configuration. Also, a possible target gene for S-oligo polyC, telomere C-repeat, has been investigated in terms of the structure, and it has been found that there are isomeric C repeat tetrads. This new discovery may give suggestion not only to understand whole mechanism for nonspecific activity of S-oligo but biological functions of telomere topologies in relation to cancer and aging. (3) Stereoselective synthesis of S-oligos, another unsolved essential subject, has been studied and use of m-chlorocresol as a leaving group in the phosphite method was found to lead to high stereoselectivity and high yield of transesterification in the basic conditions. Less