寡聚脱氧核苷酸的结构与抗降解特性的研究

合成了４段具有不同高级结构或不同修饰的寡聚脱氧核苷酸，检查它们在２０％血清中的稳定性．发现：（１）寡核苷酸主要被血清中的３′外切核酸酶降解，未经修饰的线性寡核苷酸降解严重；（２）末端部分硫代修饰的寡核苷酸稳定性明显提高；（３）自身互补形成的配对结构可有效保护３′末端．具有４个以上（含４个）ＧＣ对的３′端发夹结构寡核苷酸，其抗核酸酶的能力几乎与硫代修饰的寡核苷酸相当．

A Study on the Stability of Oligodeoxyribonucleotides with Different Structure and Modification

The stabilities of four oligodeoxyribonucleotides(ODN) with different secondary structure and different modification in 20% human serum were studied.The experiment demonstrated that:1).3' exonuclease is primarily responsible for the degradation of ODN in serum,most of the unmodified linear ODN is seriously degraded in serum;2).ODN containing three phosphorothioate bonds in its 3' and 5'ends have increased nuclease resistance obviously;3).3' end self complementary ODNs with a hairpin loop structure have protected the 3'end from nuclease effectively,ability of nuclease resistance of ODN containing more than four CG pairs in hairpin loop of 3' end almost equal to its partial phosphorothioated component.