Figure 3.

Superposition of design and experimental structures. Models and experimental structures were superimposed by a least-squares fit of the Cα atoms of the three internal repeats of the first DARPin in the case of the two-DARPin constructs, or of the middle DARPin in the case of the three-DARPin constructs, with rmsds of 0.4 ± 0.03 Å. Models are shown in pale blue, experimental structures in red. Rmsd values for the superposition of the whole molecules are listed in Table 1, more details are given in Supplementary Tables 2 to 4. DD constructs are named aaa_Hxx_bbb, where aaa and bbb are the abbreviated names of the N- and C-terminal DARPin domains, and Hxx indicates shared helix (with xx ranging from 02 to 15). DDD constructs are named aaa_Hxx_bbb_Hyy_ccc using the same scheme. In case of complex structures, the ligand name (e.g. MBP or GFP) is inserted right after the name of the cognate DARPin domain. The three independent crystal structures of construct D12_H12_D12_H12_D12 are distinguished by the space group of the crystals, P2₁, P2₁2₁2₁ and P3₂21.