Peng Chang Geng, Damha Masad J
Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada H3A 2K6.
Nucleic Acids Res. 2005 Dec 23;33(22):7019-28. doi: 10.1093/nar/gki1003. Print 2005.
We report the first investigation of oligoribonucleotides containing a few 1-(2-deoxy-2-alpha-C-hydroxymethyl-beta-D-ribofuranosyl)thymine units (or 2'-hm-dT, abbreviated in this work as 'H'). Both the 2'-CH2O-phosphoramidite and 3'-O-phosphoramidite derivatives of H were synthesized and incorporated into both 2',5'-RNA and RNA chains. The hybridization properties of the modified oligonucleotides have been studied via thermal denaturation and circular dichroism studies. While 3',5'-linked H was shown previously to significantly destabilize DNA:RNA hybrids and DNA:DNA duplexes (modification in the DNA strand; DeltaT(m) approximately -3 degrees C/insert), we find that 2',5'-linked H have a smaller effect on 2',5'-RNA:RNA and RNA:RNA duplexes (DeltaT(m) = -0.3 degrees C and -1.2 degrees C, respectively). The incorporation of 3',5'-linked H into 2',5'-RNA:RNA and RNA:RNA duplexes was found to be more destabilizing (-0.7 degrees C and -3.6 degrees C, respectively). Significantly, however, the 2',5'-linked H units confer marked stability to RNA hairpins when they are incorporated into a 2',5'-linked tetraloop structure (DeltaT(m) = +1.5 degrees C/insert). These results are rationalized in terms of the compact and extended conformations of nucleotides.
我们报道了对含有几个1-(2-脱氧-2-α-C-羟甲基-β-D-呋喃核糖基)胸腺嘧啶单元（或2'-hm-dT，在本工作中简称为“H”）的寡核糖核苷酸的首次研究。合成了H的2'-CH2O-亚磷酰胺和3'-O-亚磷酰胺衍生物，并将其掺入2',5'-RNA和RNA链中。通过热变性和圆二色性研究对修饰寡核苷酸的杂交特性进行了研究。虽然先前已表明3',5'-连接的H会显著破坏DNA:RNA杂交体和DNA:DNA双链体的稳定性（DNA链中的修饰；ΔTm约为-3℃/插入），但我们发现2',5'-连接的H对2',5'-RNA:RNA和RNA:RNA双链体的影响较小（ΔTm分别为-0.3℃和-1.2℃）。将3',5'-连接的H掺入2',5'-RNA:RNA和RNA:RNA双链体中被发现更具去稳定性（分别为-0.7℃和-3.6℃）。然而，值得注意的是，当2',5'-连接的H单元掺入2',5'-连接的四环结构时，它们会赋予RNA发夹显著的稳定性（ΔTm = +1.5℃/插入）。这些结果根据核苷酸的紧凑和伸展构象得到了合理的解释。
