Secondary structure and topology of SOTI-III. (a) Secondary-structure elements of SOTI-III. The four loops (mainly β-turns) are labelled L1–L4. Green arrows indicate the three β-strands. The short helix α1 is colored purple. Disulfide bonds are drawn as black lines. The cysteine residues involved are labelled I–VI. The red U-shaped line symbolizes the β-hairpin with a γ-turn of the inhibitor loop L4. (b) Topology of SOTI-III. Residue numbers for boundaries of secondary-structure elements are shown. The coloring of secondary-structure elements is the same as in (a).