Prephenate dehydrogenase, aromatic

Figure 4. Enzymes of Rhizobium (a) and Lemna (b) proposed as sites of glyphosate inhibition of aromatic amino acid synthesis. Abbreviations CM, chorismate mutase PDH, prephenate dehydrogenase and PD, prephenate dehydratase.

Prephenate (26) is converted to phenylpyruvate (28) in many bacterial systems. In some organisms, such as Escherichia coli, prephenic acid also is oxidatively aromatized to / -hydroxyphenylpyruvic acid (29) by a soluble, NAD+-de-pendent enzyme, prephenate dehydrogenase. p-Hydroxy-phenylpyruvic acid is then transaminated by the addition of L-glutamate and pyridoxal phosphate to yield L-tyrosine (30). 

---