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. Author manuscript; available in PMC: 2013 Aug 1.
Published in final edited form as: Curr Opin Chem Biol. 2012 Jun 5;16(3-4):253–259. doi: 10.1016/j.cbpa.2012.05.179

Figure 2.

Figure 2

Toehold exchange and seesaw gate function and implementation [13]. (A) A ssDNA input binds to a complementary toehold (red) on a seesaw gate and – through strand migration – replaces an output strand of the dsDNA that is then capable of the reverse reaction via a separate toehold (green). (B) A functional AND gate that takes input molecules A and B and outputs G. The left side presents a simplified overview while the right includes molecular detail. At seesaw gate 1, inputs (A and B) displace a strand of DNA (C) that then encounters threshold gate 1(E–F). This gate quickly and irreversibly turns C into waste by having a larger complementary overhang than that of molecule G–H. Only after threshold molecules have been depleted will C bind to G–H and produce the output strand G.