Figure 9
From: An ant colony optimisation algorithm for the 2D and 3D hydrophobic polar protein folding problem
Illustration and comparison of difficult structures for PERM and ACO-HPPFP-3 in 3D. Left side: Lowest energy conformation of random sequence R50-9 (50 amino acids, energy -30), which is harder for PERM when folding from the left end than for ACO-HPPFP-3; with a cut-off time of 1 CPU hour, ACO-HPPFP-3 reached this energy in 10 out of 10 runs with t exp = 1000 CPU seconds, while PERM failed to find a conformation with this energy in 7 out of 10 runs when folding from the left end (t1 = 9 892, t2 = 2, t exp = 3 CPU seconds). Right side: Lowest energy conformation of random sequence R50-7 (50 amino acids, energy -38), which is much harder for ACO-HPPFP-3 than for PERM; with a cut-off time of 1 CPU hour, PERM reached this energy in two out of 10 runs when folding from the left and in 10 of 10 runs when folding from the right end in t1 = 15 322, t2 = 46, t exp = 92 CPU seconds, while the lowest energy reached by ACO-HPPFP-3 over ten runs was -37.