Figure 2: Walking mechanism, measured and simulated CD spectra at each station.

(a) Walking mechanism. Initially, the walker resides at station I. On addition of blocking strand a and removal strand , two toehold-mediated strand-displacement reactions occur simultaneously. Blocking strand a triggers the dissociation of the walker’s feet from footholds A. Row A is then site-blocked. Meanwhile, removal strand releases blocking strand c from footholds C. Row C is therefore site activated to bind the feet of the walker. Subsequently, the walker carries out one step forward, reaching station II. For simplicity, only the front line of the associated strands is shown. (b) Measured CD spectra at different stations. (c) Simulated CD spectra at different stations. The right-handed preference at station III was not included in the calculation.