Nitinol wire is used to encode a three-dimensional structure in a linear chain. The folding of the structure progresses sequentially along the rigid wire from one end using only short-range forces. Three different shapes are constructed, an overhand pseudoknot, a protein structure with α-helices, and a protein structure without α-helices. The overhand pseudoknot was designed to be noncommutative so that forward folding along the chain results in the correct structure whereas reverse folding does not. The manipulation of nitinol wire structures leads to simple empirical rules for folding for noncommutative pseudoknots. Suggestions for additional noncommutative pseudoknot structures that can be designed both from wire and from DNA or RNA are given. The folding also can be accomplished using ordinary stiff wire. The folding of the wire provides an intuitive way to visualize sequential folding freed from a lattice.
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