Sequence dependent effects in methylphosphonate deoxyribonucleotide double and triple helical complexes.
Sequence dependent effects in methylphosphonate deoxyribonucleotide double and triple helical complexes.
复制标题
甲基膦酸脱氧核糖核苷酸双螺旋和三螺旋复合物中的序列依赖性效应。
DOI：
10.1093/nar/18.12.3545
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发表时间：
1990
影响因子：
14.9
通讯作者：
Wilson,WD
中科院分区：
文献类型：
--
作者：
Kibler-Herzog,L;Kell,B;Zon,G;Shinozuka,K;Mizan,S;Wilson,WD
用正常磷酸二酯（dA19、dT19、dU19）或膦酸甲酯（dA*19、dT*19、dU*19）键制备了含有A、T或U19个重复碱基的脱氧核糖寡核苷酸。通过热熔和凝胶电泳研究了这些链在1:1和1:2摩尔比（嘌呤：嘧啶）下的配合物。含有甲基膦酸盐链的配合物的稳定性有显著的序列依赖性差异。dA*19与dt19或du19的双相具有尖锐的熔化曲线，增加了Tm值，并且相对于未修饰的“母体”双相，Tm相对于log（钠离子活度）图的斜率降低了约一半。然而，具有dT*19或dU*19的da19双相化合物具有更宽的熔化曲线，在大多数盐浓度下Tm值降低，斜率小于未修饰的双相化合物的十分之一。在嘧啶甲基膦酸配合物中，由于磷酸盐电荷斥力减少而产生的双相稳定被位阻和其他取代基效应所抵消。dA19+ 2dt19和dA19+ 2dU19的三螺旋配合物在Na+或Mg+浓度增加时保持稳定，可通过双相熔融曲线和凝胶电泳检测。然而，令人惊讶的是，即使在非常高的盐浓度下，当任何正常链被甲基膦酸盐链取代时，也不会形成三螺旋结构。由于与甲基膦酸盐的三螺旋配合物对较短的低聚物有报道，对较大的低聚物的抑制可能因其取代的长度和程度而异。
Deoxyribooligonucleotides containing 19 repeating bases of A, T or U were prepared with normal phosphodiester (dA19, dT19, dU19) or methyl-phosphonate (dA*19, dT*19, dU*19) linkages. Complexes of these strands have been investigated at 1: 1 and 1: 2 molar ratios (purine: pyrimidine) by thermal melting and gel electrophoresis. There are dramatic sequence dependent differences in stabilities of complexes containing methylphosphonate strands. Duplexes of dA*19with dT19or dU19have sharp melting curves, increased Tm values, and slopes of Tm versus log (sodium ion activity) plots reduced by about one half relative to their unmodified ‘parent’ duplexes. Duplexes of dA19with either dT*19or dU*19, however, have broader melting curves, reduced Tm values at most salt concentrations and slopes of less than one tenth the values for the unmodified duplexes. Duplex stabilization due to reduced phosphate charge repulsion is offset in the pyrimidine methylphosphonate complexes by steric and other substituent effects. Triple helical complexes with dA19+ 2dT19and dA19+ 2dU19, which can be detected by biphasic melting curves and gel electrophoresis, are stable at increased Na+or Mg+2concentrations. Surprisingly, however, no triple helix forms, even at very high salt concentrations, when any normal strand(s) is replaced by a methylphosphonate strand. Since triple helical complexes with methylphosphonates have been reported for shorter oligomers, inhibition with larger oligomers may vary due to their length and extent of substitution.