L-Saccharopine is a product of breakdown of essential amino acid Lysine (L468895). Saccharopine is also part of the a-aminoadipate pathway of fungal lysine biosynthesis.
Higashino, K., et al.: Biochem. Biophys. Res. Commun., 20, 285 (1965); Johansson, E., et al.: Structure, 8, 1037 (2000)