Jain Akash K, Awasthi Satish Kumar, Tandon Vibha
Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi 110007, India.
Bioorg Med Chem. 2006 Sep 15;14(18):6444-52. doi: 10.1016/j.bmc.2006.05.034. Epub 2006 Jun 12.
Tethering of BBZPNH2, an analogue of the Hoechst 33258, with a 14 nucleotide long DNA sequence with the help of succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate (SMCC), a heterobifunctional crosslinking reagent, using DMF/ water as solvent yields a conjugate which effectively stabilizes the triple helix. The above conjugate was hybridized with 26 bp long double stranded (ds) DNA having 14 bp long polypurine-polypyrimidine stretch to form a pyrimidine motif triple helix. The above conjugate increases the thermal stability of both the transitions, that is, triple helix to double helix by 12 degrees C and double helix to single strand transition by 16 degrees C for the triple helix formed with conjugated TFO over the triple helix made from non-conjugated TFO. Fluorescence and circular dichroism spectra recorded at different temperatures confirm the presence of minor groove binding bisbenzimidazole in the AT-rich minor groove of dsDNA even after the major groove bound TFO separates out.
借助异双功能交联剂琥珀酰亚胺基-4-(N-马来酰亚胺甲基)环己烷-1-羧酸酯(SMCC)，以N,N-二甲基甲酰胺/水为溶剂，将Hoechst 33258的类似物BBZPNH2与一段14个核苷酸长的DNA序列连接，得到一种共轭物，该共轭物能有效稳定三链螺旋结构。上述共轭物与一段26 bp长的双链(ds)DNA杂交，该双链DNA具有14 bp长的聚嘌呤-聚嘧啶区段，形成嘧啶基序三链螺旋。对于由共轭的三链形成寡核苷酸(TFO)形成的三链螺旋，上述共轭物使三链螺旋到双链螺旋以及双链螺旋到单链转变这两种转变的热稳定性均有所提高，分别提高了12℃和16℃。与由非共轭TFO形成的三链螺旋相比。在不同温度下记录的荧光和圆二色光谱证实，即使在大沟结合的TFO分离后，dsDNA富含AT的小沟中仍存在小沟结合双苯并咪唑。
