(a) The A1-peptide ligands (grey strands) are only partially complementary to the cA1 strands (orange) protruding out of the origami plane, leaving six nucleobases available for attachment of a fully complementary sequence A1(22) (black), with consequent displacement of the A1-peptide conjugate. (b) Gel electrophoresis analysis of purified DNA cages, either unloaded (lanes 1–3) or DegP-loaded (lanes 4–6), upon treatment with 0, 10 or 100 equimolar amounts of A1(22). The reaction was let at 30 °C overnight. The results indicate protein-trapping despite successful displacement of the peptide ligands. Lane M contained 1 kbp DNA ladder (Roth). The DNA origami structures migrate between the 1.5 and 2.0 kbp bands of the ladder. Gel running conditions: 0.75% agarose in 1 × TBEMg, at 80 V for 2 h at 4 °C. The gel was scanned with a Typhoon FLA 9000 at different wavelengths to record the presence of DegP protein (Alexa647), peptide ligands (Flc) and DNA (upon ethidium bromide staining). Full gel is shown in Supplementary Fig. 58. (c) Schematic representation of the products obtained in each gel lane, before and after single-strand displacement reactions.