Institut für Biochemie, Ernst-Moritz-Arndt-Universität Greifswald, Felix-Hausdorff-Strasse 4, 17487 Greifswald (Germany).
Angew Chem Int Ed Engl. 2015 May 4;54(19):5588-91. doi: 10.1002/anie.201411887. Epub 2015 Mar 16.
A unimolecular G-quadruplex with a hybrid-type topology and propeller, diagonal, and lateral loops was examined for its ability to undergo structural changes upon specific modifications. Substituting 2'-deoxy-2'-fluoro analogues with a propensity to adopt an anti glycosidic conformation for two or three guanine deoxyribonucleosides in syn positions of the 5'-terminal G-tetrad significantly alters the CD spectral signature of the quadruplex. An NMR analysis reveals a polarity switch of the whole tetrad with glycosidic conformational changes detected for all four guanine nucleosides in the modified sequence. As no additional rearrangement of the overall fold occurs, a novel type of G-quadruplex is formed with guanosines in the four columnar G-tracts lined up in either an all-syn or an all-anti glycosidic conformation.
研究了一种具有混合拓扑结构和推进器、对角和侧环的单分子 G-四链体，以研究其在特定修饰下发生结构变化的能力。用具有反式糖苷构象倾向的 2'-脱氧-2'-氟类似物替代顺式位置的两个或三个鸟苷脱氧核苷，显著改变了四链体的 CD 光谱特征。NMR 分析显示整个四联体的极性发生了转换，并且在修饰后的序列中所有四个鸟嘌呤核苷都检测到糖苷构象发生了变化。由于整个折叠没有发生额外的重排，因此形成了一种新型的 G-四链体，其中四个柱状 G-链中的鸟嘌呤核苷排列成全顺式或全反式糖苷构象。
