图11. RET G4-DNA与秋水仙碱复合物的结构(橙色).(a)能量最低的20个结构的集合，碱基G14构象是灵活的；(b)一个复合物的构象，芳香七元环与苯环之间呈27.5°；(c)自由态RET G4-DNA的结构；(d)秋水仙素(橙色球棍模型显示)在复合物结构中位置与自由态RET G4-DNA中的G3-G9-G13-G19四集体平面中的碱基G14对比.在图(a)~(c)中，由4个syn鸟嘌呤组成的G-四集体分别为洋红色线和卡通模式，anti鸟嘌呤组成的G-四集体分别以青色和卡通模式显示.在所有图中：碱基G14是深灰色的线条和卡通模式展示；碱基G16和T20分别为绿线和卡通模式展示；碱基G4、C5、G6和C10为小麦色或卡通模式展示.所有非极性质子都没有显示出来^[61]

Fig.11. Structure of RET G4-DNA in complex with colchicine (in orange). (a) The ensemble of 20 structures with the lowest energy. Base G14 is flexible; (b) One conformer of the complex. An angle 27.5° was formed between aromatic seven-membered ring and phenyl ring; (c) The structure of free RET G4-DNA; (d) The position of colchicine (in orange) relative to G14 (in green) above G3-G9-G13-G19 tetrad (in cyan) at 3'-end in the complex structure, compared to structure of free RET G4-DNA (in line mode, except the base G14 which was termed as G14 free and displayed in blue stick). In (a)~(c), the G-tetrad composed by four syn guanines was in magenta line and cartoon modes, respectively. The G-tetrads composed by anti- guanines were shown in cyan lines and cartoon modes, respectively. In all figures, base G14 was in deep-gray lines and cartoon modes. Bases G16 and T20 were in green lines and cartoon modes, respectively. Bases G4, C5, G6 and C10 in loops were in wheat lines or cartoon modes. All nonpolar protons were not displayed^[61]