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对包含连续鸟嘌呤的寡核苷酸所形成两种反平行四链ＤＮＡ（统称ｌｏｏｐＧ４）的螺旋体部分进行了计算机模拟，给出了各种结构参数，发现ｌｏｏｐＧ４中的磷酸基团呈疏密相间的分布，导致与其抗衡的Ｋ＋亦呈疏密相间的分布。与先前做的平行四链ＤＮＡ相比较，平行Ｇ４的构象能最低，二沟Ｇ４和三沟Ｇ４次之。ｌｏｏｐＧ４中Ｇ四聚体的两种不同堆积方式以背对背的堆积能为低，为实验结果提供了理论支持。还探讨了能量优化过程中Ｇ４－ＤＮＡ的构象变化趋势，提示了金属离子的不同类型或不同浓度可能会导致Ｇ４－ＤＮＡ构象的改变
The spirochetes of two anti-parallel four-stranded DNAs (collectively, loopG4) formed by continuous guanine-containing oligonucleotides were computerized and various structural parameters were given. It was found that the phosphate groups in loopG4 were sparsely dense Of the distribution, leading to its contend with the K + was also dense and white distribution. Compared with the previous parallel four-stranded DNA, the conformational energy of parallel G4 is the lowest, followed by two-channel G4 and three-channel G4. The two different stacking modes of G-tetramers in loopG4 provide low back-to-back stacking energy and provide theoretical support for the experimental results. The conformational trends of G4-DNA during energy optimization were also explored, suggesting that different types or concentrations of metal ions may result in changes in G4-DNA conformation