Detection of triple helix DNA formation of guanine-rich oligonucleotide in sodium ion abundant buffer by cross-checking FRET scheme

In this Letter, the effects of Na+ and Mg2+ on the formation of triple helix DNA were examined by cross-checking of FRET signal from the different kinds of samples. Sodium abundant solution has not been thoroughly examined for the triple helix DNA experiment, although one can often face to the biological environment which has abundant Na+ ion. The result reconfirms that Mg2+ ion helps the oligonucleotides to form both double helix and triple helix DNA. It was conjectured and confirmed that Na+ plays a complex role, being configured by the polyelectrolyte effect and the effect of K+ on guanine-rich oligonucleotide.