Figure 6.

(A) Representative routes of dihedral-angle change in transition from helix to extended conformation on Ramachandran plot. A majority of residues took route from right-handed α-helix (region 1) to extended forms (regions 4 and 5) upon tensile extension, going over energy barriers in regions 2 and 3. Regions 1-5 are marked with dotted circles. A few of them took the route to region 5 through the dotted arrow. Blue regions represent low-energy regions for poly-Ala (52). (B) A model of poly-L-Ala α-helix shows preferred rotation around ϕ and ψ dihedral angles, when viewed from C^α as predicted by our SMD simulations (green, carbon atoms; blue, nitrogen atoms; red, oxygen atoms; white, hydrogen atoms).