The hypothesized pigmentation species HGA and BQA are distinguishable by their characteristic chemical shifts (Supplementary Table ). Previous ssNMR studies on AKU cartilage tissue only indicated a global broadening of the NMR signals . With recent developments in dynamic nuclear polarisation (DNP) magic angle spinning solid-state NMR , whereby the observed signal can be enhanced by factors of one to two orders of magnitude, it is attractive to revisit the ssNMR approach for studying AKU tissue.