The binding of a rHS TFO in the major groove of dsDNA yields an antiparallel triplex, stabilized by the A:AT and G:GC base triads with two hydrogen bonds each (Fig. ). Notable differences between nHS and rHS TFOs are that rHS TFOs are composed of purines rather than pyrimidines (Fig. ) and that they have an overall weaker binding affinity. Additionally, the stabilities of nHS and rHS triplexes inversely depend on the guanine content of target domains in addition to TFO length. Parallel nHS triplexes favour lower G% because of the charge-repulsion in protonated cytosines; conversely, antiparallel rHS triplexes are stabilized by high G% (Supplementary Fig. ). An important and convenient similarity is that rHS triplexes also have a reported average helical twist close to 12 bt per triplex turn . This is interesting because it implies that nHS triplex origami designs can be refolded as rHS structures by simply using a reverse-complement staple set, without further design optimization.