Arogenate dehydrogenase

This enzyme [EC 1.3.1.43], also referred to as arogenate dehydrogenase and pretyrosine dehydrogenase, catalyzes the reaction of arogenate with NAD+ to produce tyrosine, NADH, and carbon dioxide. Both prephenate and D-prephenyllactate can act as alternative substrates. 

OCTOPINE DEHYDROGENASE ARGININOSUCCINATE LYASE ARGININOSUCCINATE SYNTHETASE ARISTOLOCHENE SYNTHASE Arogenate dehydrogenase,... 

Figure 7. Variation of arogenate dehydrogenase levels as a function of the physiological phase of growth in suspension cultures of Nicotiana sil-vestris. A stationary-phase inoculum was diluted into fresh medium and followed throughout the lag (L), exponential (E), and stationary (S) phases of growth. The hatched bar indicates the activity levels of EE cells, i.e., cells maintained continuously in exponential growth for 10 or more generations (53). Profiles are shown in which activity is related to soluble protein (specific activity), to cell number, or to dry weight.

Chorismate mutase 2 prephenate aminotransferase 3 prephenate dehydratase 4 prephenate dehydrogenase 5 arogenate dehydrogenase 6 phenylalanine aminotransferase 7 tyrosine aminotransferase 8 tyrosine 3-monooxygenase 9 phenylalanine 4-monooxygenase (C 2.6.5)... 

Fig. 5. Variation of levels of enzyme activity during growth of cultured cells of N. silvestris. Dashed line indicates transfer of cells in late-exponential growth to fresh medium (16-fold dilution). Data shown at the upper right is a portion of a growth curve obtained between 30 and 32 generations of continuous exponential growth. The bottom section shows specific activities (nmoles/min/mg) obtained for DAHP synthase-Mn [DS-Mn], DAHP synthase-Co [DS-Co], and arogenate dehydrogenase [AGN DH] in samples taken from cultures at times (in days) aligned with the values of specific activity.

Fig. 9. Sequential pattern of allosteric control over biosynthesis of aromatic amino acids in the plastid compartment. In the presence of excess aromatic amino acids, L-tyrosine (TYR) inhibits arogenate dehydrogenase, L-phenylalanine (PHE) inhibits arogenate dehydratase and L-tryptophan (TRP) inhibits anthranilate synthase. The three aromatic amino acids exert allosteric inhibition (-) or activation (+) effects upon chorismate mutase-1 as symbolized. However, activation dominates over inhibition. The outcome of these events is to trap L-arogenate (AGN) between the various foci of control in the pathway. As shown symbolically, -arogenate (AGN) then acts to feedback inhibit DAHP synthase-Mn.

L-Tyrosine regulation and biosynthesis via arogenate dehydrogenase in suspension-cultured cells of Nicotiana silvestris (Speg. et Comes). Planta 156 233-240. 

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