Abstract: The single stranded DNA or RNA sequences having rich stretches of consecutive guanines can fold into four-stranded struc-tures known as G-quadruplexes, which play crucial roles in chromosomal maintenance, transcription and translation, as well as otherbiological processes. The putative G-quadruplex-forming sequences are wildly spread among the human genome and mRNA, especiallymore frequent in the telomere and promoters. Here, we focused on the different characteristics of the interlocked G-quadruplexes adopt-ed by sequence d(G3AG2T3G3AT) in the presence of sodium and potassium ions, respectively. The experimental results showed that d (G3AG2T3G3AT) at first folded into a kinetically favorable conformation in K+solution, and then spontaneously converted to a thermo-dynamically stable conformation with an extremely high thermal stability. Secondly, upon K+ion titration, the interlocked G-quadruplex structure even well pre-folded in an excessive amount of Na+still enabled a ready conversion to the thermodynamically stable conforma-tion ultimately stabilized by K+. This interlocked G-quadruplex will be expected applicable in the field of nanomaterial due to its con-siderable water-solubility, biocompatibility and extreme stability.

Key words: interlocked G-quadruplex, nuclear magnetic resonance (NMR), circular dichrosim(CD), stability, nanomaterial