The biosynthesis of lysine starts with oxoglutaric acid interacting with acetyl-coa through a homocitrate synthase resulting in the release of homocitric acid. This reaction may happen in the cytosol or in the mitochondria. The homocitric acid spontaneously releases water an is transformed into cis-homoaconitate, The cis-homoaconitate reacts with homoaconitase resulting in the release of water and a homoisocitrate. Homoisocitrate reacts with a NAD dependent homoisocitrate dehydrogenase resulting in the release of a carbon dioxide, a NADH and a oxoadipic acid. These set of reactions happen in the mitochondria. Oxoadipic acid reacts with a glutamic acid resulting in the release of oxoglutaric acid and aminoadipic acid. The aminoadipic acid reacts with a holo-[LYS2 peptidyl-carrier-protein] through an ATP driven L-2-aminoadipate reductase resulting in the release of AMP, pyrophosphate and L-2-aminoadipyl-[lys2 peptidyl-carrier-protein]. This resulting element reacts with a NADPH dependent L-2-aminoadipate reductase resulting in the release of allysine. Allysine reacts with a glutamic acid through a NADPH dependent saccharopine dehydrogenase resulting in the release of water, NADP and saccharopine. Saccharopine reacts with a water molecule and a NAD dependent saccharopine dehydrogenase resulting in the release of oxoglutaric acid and L-lysine. This last reaction is reversible and leads to the degradation of lysine

Lysine Metabolism References