Cummins L L, Owens S R, Risen L M, Lesnik E A, Freier S M, McGee D, Guinosso C J, Cook P D
ISIS Pharmaceuticals, Carlsbad, CA 92008, USA.
Nucleic Acids Res. 1995 Jun 11;23(11):2019-24. doi: 10.1093/nar/23.11.2019.
The nuclease stability and melting temperatures (Tm) were compared for fully modified oligoribonucleotide sequences containing 2'-fluoro, 2'-O-methyl, 2'-O-propyl and 2'-O-pentyl nucleotides. Duplexes formed between 2' modified oligoribonucleotides and RNA have typical A-form geometry as observed by circular dichroism spectroscopy. Modifications, with the exception of 2'-O-pentyl, were observed to increase the Tm of duplexes formed with complementary RNA. Modified homoduplexes showed significantly higher Tms, with the following Tm order: 2'-fluoro:2'fluoro > 2'-O-propyl:2'-O-propyl > 2'-O-methyl:2'-O- methyl > RNA:RNA > DNA:DNA. The nuclease stability of 2'-modified oligoribonucleotides was examined using snake venom phosphodiesterase (SVPD) and nuclease S1. The stability imparted by 2' modifications was observed to correlate with the size of the modification. An additional level of nuclease stability was present in oligoribonucleotides having the potential for forming secondary structure, but only for 2' modified oligoribonucleotides and not for 2'-deoxy oligoribonucleotides.
对含有2'-氟、2'-O-甲基、2'-O-丙基和2'-O-戊基核苷酸的完全修饰的寡核糖核苷酸序列的核酸酶稳定性和解链温度（Tm）进行了比较。通过圆二色光谱观察到，2'修饰的寡核糖核苷酸与RNA形成的双链体具有典型的A-型构象。除2'-O-戊基外，其他修饰均能提高与互补RNA形成的双链体的Tm。修饰的同型双链体显示出明显更高的Tm，Tm顺序如下：2'-氟：2'-氟＞2'-O-丙基：2'-O-丙基＞2'-O-甲基：2'-O-甲基＞RNA：RNA＞DNA：DNA。使用蛇毒磷酸二酯酶（SVPD）和核酸酶S1检测了2'修饰的寡核糖核苷酸的核酸酶稳定性。观察到2'修饰赋予的稳定性与修饰的大小相关。具有形成二级结构潜力的寡核糖核苷酸中存在额外水平的核酸酶稳定性，但仅适用于2'修饰的寡核糖核苷酸，不适用于2'-脱氧寡核糖核苷酸。
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