Arogenic acid is an intermediate in the biosynthesis of phenylalanine and tyrosine. At physiological pH it exists as its conjugate base arogenate as the acid form is unstable.
Arogenate is synthesized from prephenate by transamination. This reaction can be catalyzed by several enzymes, including aromatic-amino-acid transaminase,[1] aspartate—prephenate aminotransferase[2] and glutamate—prephenate aminotransferase:[3]
prephenate + amino acid → arogenate + keto acid
The amino acid in this case can be either aspartate or glutamate, which turn into oxaloacetate and 2-oxoglutarate, respectively.
Arogenate is then turned into either phenylalanine or tyrosine. When prephenate dehydratase[4] or arogenate dehydratase[5] act upon arogenate, phenylalanine is produced:
arogenate → phenylalanine + H2O + CO2
When arogenate dehydrogenase,[6] arogenate dehydrogenase (NAD(P)+)[7] or arogenate dehydrogenase (NADP+)[8] acts upon arogenate, tyrosine is produced:
arogenate + NAD(P)+ → tyrosine + NAD(P)H + H+ + CO2