Fig. 3: Collagen ruptures primarily in crosslinks, but also unspecific ruptures occur everywhere.

Data were obtained from 63 independent MD simulations, including divalent and trivalent crosslink setups, with different collagen sequences and pulling conditions, as described in the methods section. For simulations with trivalent crosslinks, we used the deprotonated BDEs of PYD. In both panels b and c the same data is presented in two different reference systems. a Left side: Location of residues and crosslinks in our model along the fiber axis. Triple helices with the same phase are in the same color, respectively. Upper and lower residues participating in the same crosslinks (blue) appear in the same residue position in the model; see, for example, the blue encircled area. This view is used in panel b. Right side: Crosslinks along a whole 300 nm collagen molecule occur at the beginning (cyan area) and at the end of a triple helix (magenta area), shown as a cartoon with coloring as in the structure on the left. This reference system, counting along the collagen molecule, is used in panel c. b Propensity of bond breakages in our collagen model. Most ruptures concentrate in the crosslinked area, while there are some scattered backbone ruptures. Inset: Pie chart of summed-up ruptures in the crosslinks vs. the backbones in the crosslinked area (up to five residues before/behind) vs. elsewhere in the backbone. c Propensity of bond breakages within collagen fibrils. The crosslinked areas at the beginning and end of the molecules, as marked exemplary for the N-terminal crosslink in the shaded areas, are most prone to rupture. Note that both in b and c we only show data points where at least one rupture happened.