Collagen is a foundational class of proteins, found in all animals in large amounts. It's weird -- it has an unusual amino acid, hydroxyproline, that is not directly specified in the standard genetic code (instead, it is made by modification of proline after the protein has been synthesized; this conversion requires vitamin C and its failure is one of the pathologies of scurvy).
One version of collagen, Collagen IV, has this weird sulfur-nitrogen double bound that is produced (again, by post-translational modification) using bromine as a reagent, and for this reason bromine (as bromide) in tiny amounts is a necessary trace element in diets. This last fact was only discovered in 2014.
One version of collagen, Collagen IV, has this weird sulfur-nitrogen double bound that is produced (again, by post-translational modification) using bromine as a reagent, and for this reason bromine (as bromide) in tiny amounts is a necessary trace element in diets. This last fact was only discovered in 2014.
https://pubmed.ncbi.nlm.nih.gov/24906154/