Α-Aminoadipic acid

α-Aminoadipic acid is one of the metabolic precursor in the biosynthesis of lysine through α-aminoadipate pathway. Its conjugate base is α-aminoadipate, which is the prevalent form at physiological pH.

α-Aminoadipic acid has a stereogenic center and can appear in two enantiomers, L -α-aminoadipate and D -α-aminoadipate. The L -enantiomer appears during lysine biosynthesis and degradation, whereas the D -enantiomer is a part of certain antibiotics.

Lysine degradation
Through saccharopine and allysine, lysine is converted to α-aminoadipate, which is then degraded all the way to acetoacetate. Allysine is oxidized by aminoadipate-semialdehyde dehydrogenase:


 * allysine + NAD(P)+ ↔ α-aminoadipate NAD(P)H + H+

α-Aminoadipate is then transaminated with α-ketoglutarate to give α-ketoadipate and glutamate, respectively, by the action of 2-aminoadipate transaminase:


 * α-aminoadipate + α-ketoglutarate ↔ α-ketoadipate + glutamate

Lysine biosynthesis
α-Aminoadipate appears during biosynthesis of lysine in several yeast species, fungi, and certain protists. During this pathway, which is named after α-aminoadipate, the same steps are repeated in the opposite order as in the degradation reactions, namely, α-ketoadipate is transaminated to α-aminoadipate, which is then reduced to allysine, allysine couples with glutamate to give saccharopine, which is then cleaved to give lysine.

Importance
A 2013 study identified α-aminoadipate as a novel predictor of the development of diabetes and suggested that it is a potential modulator of glucose homeostasis in humans.

D -α-Aminoadipic acid is a part of the antibiotic cephalosporin C.