Ali O M, Franch T, Gerdes K, Pedersen E B
Department of Chemistry and Department of Molecular Biology, Odense University, Campusvej 55,DK-5230 Odense M, Denmark.
Nucleic Acids Res. 1998 Nov 1;26(21):4919-24. doi: 10.1093/nar/26.21.4919.
It is possible to enhance targeting of a DNA stem flank domain with a complementary DNA when it is conjugated with diphenyl ether at the branch point. The nucleoside 2'-deoxy-5-methyl- N 4-(4-phenoxyphenyl)cytidine (5) was synthesized from thymidineby tritylation, acetylation, amination via 2,4, 6-trimethylbenzenesulfonyl activation and subsequent de-protection. When a three-way junction is formed with a bulged nucleoside 5 at the branch point, the thermal melting temperature was increased by 9 degreesC when compared with wild-type DNA. When hybridizing to one of the flanks at a stem allowing coaxial stacking to the stem, modification at the branch point resulted in DeltaTm= 5.8 degreesC. For targeting to RNA the results were more ambiguous. RNase H activity was observed in some cases when an intercalating aromatic ring was addressed at the branch point. RNase H activity was observed even for a short 7mer ODN.
当与二苯醚在分支点处共轭时，用互补DNA增强DNA茎侧翼结构域的靶向性是可能的。核苷2'-脱氧-5-甲基-N4-(4-苯氧基苯基)胞苷(5)由胸苷通过三苯甲基化、乙酰化、经2,4,6-三甲基苯磺酰基活化的胺化反应及随后的去保护反应合成。当在分支点处与突出的核苷5形成三链连接时，与野生型DNA相比，热解链温度提高了9℃。当在允许与茎同轴堆积的茎处与一个侧翼杂交时，分支点处的修饰导致ΔTm = 5.8℃。对于靶向RNA，结果更不明确。当在分支点处引入嵌入芳香环时，在某些情况下观察到了RNase H活性。即使对于短的7聚体寡脱氧核苷酸也观察到了RNase H活性。
