Fig. 3: Vibrations associated with amide-I/II/III bands for different secondary structures.
From: Protein secondary structure in spider silk nanofibrils
Structure and amide-I/II/III vibrational modes in a an antiparallel β-(Ala)n β-sheet52,58,63. b/c a (Gly)n-II 31-helix82. b Side view (neighboring strands dimmed; not all hydrogen bonds shown). Black solid line: helix axis. c Top view of a single 31-helix (black, dashed line: recluse ribbon surface). d α-helix segment (KANADAFINSFISAAS) in the protein 2N3E (side view)83. Black, blue, red, and white spheres represent carbon (C), nitrogen (N), oxygen (O), and hydrogen (H) atoms, respectively. H-bonds are represented by light purple rods. The α-hydrogens and functional groups are not shown for β-sheet and α-helix, respectively. Amide-I/II/III modes are indicated by green dashed lines and arrows. The axes in the red boxes represent the local orthogonal coordinates.
