Figure 3.

Tunneling underneath a mortality landscape. (A) shows a 25- and a 15-step optimal point-mutation path that lead from sequences B and D to sequence C (shown in their unique native conformations), respectively. The graduations on the horizontal scale correspond to 41 different unique sequences that collectively encode 19 different structures (marked by vertical shadings, two of the regions encode for the same structure.) The −ε₀ vs. sequence profile is the mortality landscape along these point-mutation paths. The dotted arrows in A depict the “tunneling effect” of a crossover between sequences B and D that leads directly to sequence C. In this crossover, the 11-monomer segment (enclosed by dotted boxes) inherited by sequence C from parent sequence B acts similar to an “autonomous folding unit.”