Fig. 1. Structures of proteins scaffolds. Notes: cartoon-illustrations are generated using PyMol, β-sheets are shown in green, α-helix structures are displayed in yellow and disulfide bonds are colored in red. (A) Affibody (PDB ID:3MZW); (B) ANTICALIN® (PDB ID: 4GH7); (C) adnectin or monobody (PDB ID: 1TTG); (D) Knottin (PDB ID: 2IT7); (E) designed ankyrin repeat proteins (PDB ID: 1MJ0); (F) Nanofitin or Affitin (PDB ID: 4CJ2); (G) centyrins (PDB ID: 5L2H); (H) Kunitz (PDB ID: 1KTH); (I) affimer (PDB ID: 1NB5); (J) avimer (PDB ID:1AJJ); (K) Affilin based on the ubiquitin (PDB ID:1UBI); and (L) affilin based on the γ-B-crystalin (PDB ID: 2JDG).