用分子力学方法研究了 4个分子内三螺旋DNA ( 5′ d(TC) 6 d(T) m d(CT) 6 d(C) n d(AG) 6,m ,n分别为 4,3)的稳定性 ,并与相应的分子间三螺旋d(TC) 6 d(AG) 6·d(CT) 6进行了比较 .结果表明 :Loop环对分子内三螺旋的稳定性影响较小 ,但是Loop上碱基和糖环构象的变化依赖于Loop环的长度 .Loop使分子内三螺旋DNA嘌呤链的碱基堆积作用降低 ,链长增加 .三螺旋DNA的糖环构象大部分是S型 ,同时也存在N型以及其他构象 . Using molecular mechanics, the molecular dynamics of the three helical DNA (5 ’d (TC) 6 d (T) md (CT) 6 d (CT) 6 d (AG) 6 · d (CT) 6 between the three intermolecular helixs.The results showed that the loop had little effect on the stability of the intramolecular triple helix, but Loop The changes in the conformation of the base and sugar ring depend on the length of the loop loop. Loop reduces the base accumulation of the purine chain of the triple helix DNA and increases the chain length. The conformation of the sugar ring of the triple helix DNA is mostly S type There are also N-type and other conformations.