Fig. 1.

Met content in spidroin NTDs and solution structure of L6-NTD. a Number of Met residues in homologous, ~135-residue long NTD sequences of MaSp1 and MaSp2 from spider species Ea Euprosthenops australis, Lg Latrodectus geometricus, Lh Latrodectus hesperus, Nc Nephila clavipes, At Argiope trifasciata, and Nim Nephila inaurata madagascariensis (black bars). The number of Met residues in core position and/or involved in tertiary interaction are shown as gray bars. b Far-UV CD spectrum of WT-NTD (blue) and of L6-NTD (orange). c Solution NMR structure of L6-NTD (PDB ID: 6QJY) (orange) aligned with the structure of WT-NTD (PDB ID: 2LPJ) (blue). The side chains of the six Met residues that are in core position and/or involved in tertiary interaction in WT-NTD and are mutated to Leu in L6-NTD are highlighted as blue and orange sticks. The side chain of the conserved Trp (W10), helices 1–5 (H1-H5) and N-terminus (N) and C-terminus (C) are indicated. Source data of Fig. 1b are provided as Source Data file