In the pigmented cartilage spectra (Fig. , left column/red), the glycine Cα-HN signal is not as well-defined and smeared towards lower 1 H chemical shift values, which can also be seen in the H columns extracted at δ( 13 C) 42.5 ppm (Supplementary Fig. ). This indicates that the hydrogen bonds that the glycine HN are participating in are disrupted, suggesting at least partial dissociation of the collagen triple helix in the pigmented AKU cartilage sample.