4′-Cα-methyl modification. The α- and β-epimers of 4′-C-OMe-uridine and the α-epimer of 4′-C-Me-uridine monomers were synthesized and incorporated into siRNAs. The 4′α-epimers affect thermal stability only minimally and show increased nuclease stability irrespective of the 2′-substituent (H, F, OMe). The 4′β-epimers are strongly destabilizing, but afford complete resistance against an exonuclease with
化学修饰是寡核苷酸治疗剂改善代谢稳定性,摄取和活性的先决条件,无论其作用方式如何,即反义,RNAi或适体。
磷酸部分和
核糖C2'/ O2'原子是最常见的修饰位点。与2'- O-取代基相比,
核糖4'- C-取代基位于3'-和5'-相邻的
磷酸盐附近。为了研究对
核酸酶抗性的潜在有益效果我们结合2'-F和2'- ö我与4'- Cα -和4'- Cβ -OMe,和2'-F与4'- Cα甲基修饰。4′- C的α-和β-受体合成了-OMe-
尿苷和4'- C -Me-
尿苷单体的α-差向异构体,并将其掺入到siRNA中。4' α差向异构体影响热稳定性仅最低限度地和展示的2'-取代(H,F,OME)的不论增加的
核酸酶稳定性。4' β差向异构体强烈不稳定,但得到完全抵抗与
磷酸酯或
硫代磷酸酯主链外切
核酸酶。包含2'-F,4' - Cα -OMe-U,2'-F,4' - Cβ -OMe-U,2'- O Me,4' -