Simple Monovalent Metal Ion Logical Order to Regulate the Secondary Conformation of G-Quadruplex

[Image: see text] Based on the reactions of different sequences with single ions K(+), Na, NH(4)(+), double ions high + low, low + high, and triple ions with different addition orders, the best stable ion combinations of 12 quadruplexes with different DNA sequences were reported. From the fluorescence spectrum, except for HT-V15 and PW17 and AS1411 and HT-V18, the structural stability of G-quadrangle formed basically follows a certain rule. In terms of this experiment, according to circular dichroism, the antiparallel quadrupole structure has the largest proportion among quadrupole structures, and 12 optimal DNA addition schemes and sequences have been obtained through exploration. It is worth mentioning that, on the whole, the best addition scheme of AS1411 and HT-V18 is a three-ion scheme, which provides an effective reference for similar experiments in the future.