Saccharopine dehydrogenase (NAD+, L-lysine-forming)

In enzymology, a saccharopine dehydrogenase (NAD+, L-lysine-forming) (EC 1.5.1.7) is an enzyme that catalyzes the chemical reaction

N₆-(L-1,3-dicarboxypropyl)-L-lysine + NAD⁺ + H₂O L-lysine + 2-oxoglutarate + NADH + H⁺

The 3 substrates of this enzyme are N6-(L-1,3-dicarboxypropyl)-L-lysine, NAD⁺, and H₂O, whereas its 4 products are L-lysine, 2-oxoglutarate, NADH, and H⁺.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is N6-(L-1,3-dicarboxypropyl)-L-lysine:NAD+ oxidoreductase (L-lysine-forming). Other names in common use include lysine-2-oxoglutarate reductase, dehydrogenase, saccharopine (nicotinamide adenine dinucleotide,, lysine forming), epsilon-N-(L-glutaryl-2)-L-lysine:NAD oxidoreductase (L-lysine, forming), N6-(glutar-2-yl)-L-lysine:NAD oxidoreductase (L-lysine-forming), 6-N-(L-1,3-dicarboxypropyl)-L-lysine:NAD+ oxidoreductase, and (L-lysine-forming). This enzyme participates in lysine biosynthesis and lysine degradation.

Structural studies

As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 1FF9.

References

• Fujioka M, Nakatani Y (1972). "Saccharopine dehydrogenase. Interaction with substrate analogues". Eur. J. Biochem. 25 (2): 301–7. doi:10.1111/j.1432-1033.1972.tb01697.x. PMID 4339117. 
• Saunders PP, Broquist HP (1966). "Saccharopine, an intermediate of the aminoadipic acid pathway of lysine biosynthesis. IV. Saccharopine dehydrogenase". J. Biol. Chem. 241 (14): 3435–40. PMID 4287986.