In humans, Lysine is an essential amino acid, and there is no Lysine biosynthetic machinery. However, humans do degrade Lysine. Lysine is incorporated to Collagen, one of the most important components of Connective tissue and its supply is therefore required during embryonic development and early childhood (Ref.1). It is also important for Carnitine Synthesis. The main catabolic pathway for Lysine, via Saccharopine (e-N-(L-Glutaryl-2)-L-lysine), is a mitochondrial pathway leading to the formation of Acetyl-CoA (Acetyl-Coenzyme-A). Another Lysine degradation mechanism that is the Peroxisomal Pathway, via Pipecolic Acid is of less physiological importance and is mainly active in brain. The existence of two minor pathways for Lysine degradation, the Acetyllysine Pathway and the Lysine-Urea Cycle, remains to be demonstrated (Ref.2).
The Saccharopine Pathway, [...]