Detection of parallel and antiparallel DNA triplex structures in living human cells using in-cell NMR

We introduced oligodeoxynucleotides (ODNs) that form parallel and antiparallel triplex structures in vitro into living human cells and recorded their in-cell NMR spectra. Observation of landmark signals for triplex structures proved for the first time that parallel and antiparallel triplex structures are formed in living human cells. The formation of parallel and antiparallel triplex structures in living human cells is proven for the first time.