 Lysine catabolism occurs through one of several pathways, the most common of which is the saccharopine pathway.Lysine plays several roles in humans, most importantly proteinogenesis, but also in the crosslinking of collagen polypeptides, uptake of essential mineral nutrients, and in the production of carnitine, which is key in fatty acid metabolism.Lysine is also often involved in histone modifications, and thus, impacts the epigenome.