16: With increasing chain length, the width of the heat capacity peak at half maximum, a rough measure of cooperativity of folding, decreases until tertiary structure emerges at 36 residues. The melting point computed from the heat capacity curve is maximal for 18-24 residues. Similar behavior is indicated by the position and steepness of the transition in the native contacts curve (lower left). Shorter chains have fewer native contacts to provide stability, while longer chains begin to favor formation of a strand adjacent to the helix. Energy-minimized medoids for varying numbers of residues in a helical foldamer, taken from the cluster with lowest intra-cluster RMSD in each case, are shown. All uncertainties are estimated using the standard deviation from bootstrapping.