Fig. 2.

Single-molecule force spectroscopy of the hydrogel building blocks. a Schematic of the SMFS experiments performed to assess the mechanical stability of the TIP-1:Kir complex. Kir peptide was attached to the AFM cantilever through a PEG linker. TIP-1 was anchored on the substrate through a Snap tag. Depending on the protein constructs, TIP-1 can be pulled either from the N-terminus or from the C-terminus. b, c Representative force-extension curves for the rupture of the TIP-1:Kir complexes from two different pulling directions. Red lines correspond to worm-like chain (WLC) fittings. d, e The rupture force histograms for the two pulling directions. f Schematic of the polyprotein (GB1)₈. g Representative force-extension curves. Each peak represents an unfolding event of GB1 upon stretching. Cyan lines correspond to WLC fittings. h The unfolding force histogram. i Schematic of the polyprotein of (GB1-HP67)₄. j Representative force-extension curves. Only the unfolding of GB1 (high force peaks) can be detected in the traces. HP67 is mechanically labile, giving rise to the long featureless region prior to the unfolding events of GB1. k HP67 unfolds at forces lower than the detection limit of our AFM (~ 10 pN). l Schematic of the polyprotein (SH3)₈. m Representative force-extension curves. Each peak represents an unfolding event of SH3 upon stretching. Blue lines correspond to WLC fittings. n The unfolding force histogram. The pulling speed for all experiments was 400 nm s⁻¹