A guanine-rich human mature microRNA, miR-1587, was discovered to form stable intramolecular G-quadruplexes in the presence of K⁺, Na⁺ and low concentration of NH₄⁺ (25 mM) by electrospray ionization mass spectrometry (ESI-MS) combined with circular dichroism (CD) spectroscopy. Furthermore, under high concentration of NH₄⁺ (100 mM) or molecular crowding environments, miR-1587 formed a dimeric G-quadruplex through 3′-to-3′ stacking of two monomeric G-quadruplex subunits with one ammonium ion sandwiched between the interfaces. Specifically, two synthesized jatrorrhizine derivatives with terminal amine groups could also induce the dimerization of miR‐1587 G‐quadruplex and formed 1:1 and 2:1 complexes with the dimeric G-quadruplex. In contrast, jatrorrhizine could bind with the dimeric miR‐1587 G‐quadruplex, but could not induce dimerization of miR‐1587 G‐quadruplex. These results provide a new strategy to regulate the functions of miR-1587 through induction of G-quadruplex formation and dimerization.

通过电喷雾电离质谱（ESI-MS）发现，在K ⁺，Na ⁺和低浓度的NH ₄ ⁺（25 mM）存在下，富含鸟嘌呤的人类成熟microRNA miR-1587可形成稳定的分子内G四联体。）结合圆二色性（CD）光谱。此外，在高浓度的NH ₄ ^+下（100 mM）或分子拥挤环境中，miR-1587通过两个单体G-四链体亚基的3'至3'堆叠形成三聚体G-四链体，其中一个铵离子夹在界面之间。特别是，两个带有末端胺基的合成的麻风树碱衍生物也可以诱导miR-1587 G-四链体的二聚化，并与二聚体G-四链体形成1：1和2：1的复合体。相反，麻风树碱可以与二聚体miR-1587 G-四链体结合，但不能诱导miR-1587 G-四链体的二聚化。这些结果提供了通过诱导G-四链体形成和二聚化来调节miR-1587功能的新策略。