序列组成对含N7-脱氧鸟苷的寡核苷酸形成三链螺旋稳定性的影响。
Sequence composition effects on the stabilities of triple helix formation by oligonucleotides containing N7-deoxyguanosine.
作者信息
Brunar H, Dervan P B
机构信息
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
出版信息
Nucleic Acids Res. 1996 Jun 1;24(11):1987-91. doi: 10.1093/nar/24.11.1987.
A nonnatural nucleoside, 7-(2-deoxy-beta-D-erythro-pento-furanosyl)-guanine (d7G), mimics protonated cytosine and specifically binds GC base pairs within a pyrimidine - purine - pyrimidine triple helix. The differences in association constants (KT) determined by quantitative footprint titration experiments at neutral pH reveal dramatic sequence composition effects on the energetics of triple helix formation by oligonucleotides containing d7G. Purine tracts of sequence composition 5'-d(AAAAAGAGAGAGAGA)-3' are bound by oligonucleotide 5'-d(TTTTT7GT7GT7GT7GT7GT)-3' three orders of magnitude less strongly than by 5'-d(TTTTTmCTmCTmCTmCTmCT)-3' (KT = 1.5 x 10(6) M(-1) and KT > or = 3 x 10(9) M(-1) respectively). Conversely, purine tracts of sequence composition 5'-d(AAAAGAAAAGGGGGGA)-3' are bound by oligonucleotide 5'-d(TTTTmCTTTT7G7G7G7G7G7GT)-3' five orders of magnitude more strongly than by 5'-d(TTTTmCTTTTmCmCmCmCmCT)-3' (KT > or = 3 x 10(9) M(-1) and KT < 5 x 10(4) M(-1) respectively). The complementary nature of d7G and mC expands the repertoire of G-rich sequences which may be targeted by triple helix formation.
一种非天然核苷，7-(2-脱氧-β-D-赤藓戊呋喃糖基)-鸟嘌呤（d7G），模拟质子化胞嘧啶，并特异性结合嘧啶-嘌呤-嘧啶三链螺旋内的GC碱基对。在中性pH下通过定量足迹滴定实验测定的缔合常数（KT）差异揭示了，含有d7G的寡核苷酸对三链螺旋形成能量学的显著序列组成效应。序列组成为5'-d(AAAAAGAGAGAGAGA)-3'的嘌呤片段与寡核苷酸5'-d(TTTTT7GT7GT7GT7GT7GT)-3'的结合强度比与5'-d(TTTTTmCTmCTmCTmCTmCT)-3'的结合强度低三个数量级（KT分别为1.5×10(6) M(-1)和KT≥3×10(9) M(-1)）。相反，序列组成为5'-d(AAAAGAAAAGGGGGGA)-3'的嘌呤片段与寡核苷酸5'-d(TTTTmCTTTT7G7G7G7G7G7GT)-3'的结合强度比与5'-d(TTTTmCTTTTmCmCmCmCmCT)-3'的结合强度高五个数量级（KT分别≥3×10(9) M(-1)和KT＜5×10(4) M(-1)）。d7G和mC的互补性质扩展了可通过三链螺旋形成靶向的富含G序列的范围。
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