Arogenate dehydratase (ADT) (EC 4.2.1.91) is an enzyme that catalyzes the chemical reaction L-arogenate → L-phenylalanine + H2O + CO2 Hence, this enzyme has one substrate, L-arogenate, but 3 products:L-phenylalanine, H2O, and CO2. Certain forms of the protein have the potential to catalyze a second reaction, L-prephenate → L-phenylpyruvate + H2O + CO2 This enzyme participates in phenylalanine, tyrosine, and tryptophan biosynthesis (an example structure is shown to the right.