Prephenate dehydrogenase

Prephenate dehydrogenase is an enzyme found in the shikimate pathway, and helps catalyze the reaction from prephenate to tyrosine.

Nomenclature
Gene: (Saccharomyces Cerevisiae) TYR1

Shikimate pathway: Arogenate/Prephenate (ADH/PDH). Although in the shikimate pathway arogenate and prephenate dehydrogenase catalyze different reactions, they can at times be used interchangeably.
 * TyrA (tyrosine A: within the tyrosine pathway)
 * Prephenate dehydrogenase
 * Prephenate (Nicotinamide adenine dinucleotide phosphate) dehydrogenase
 * Prephenate dehydrogenase (NADP)
 * NADP+ oxidoreductase

Homology
This enzyme so far has been found in sixteen different organisms; twelve different kinds of bacteria (mostly cyanobacteria) and four different kinds of plants (mostly different kinds of beans).

Bacteria organisms (examples): Acenitobacter calcoaceticus, Fischerella sp., Flavobacterium so., Comamonas testosteroni, and nostoc sp.

Plant organisms: phaseolus coccineus, phaseolus vulgaris, vicia faba, vigna radiata

Function
Present in the shikimate pathway, in the pathway to synthesize tyrosine (a non-essential amino acid in both plants and animals). It catalyzes the oxidative decarboxylation reaction of prephenate to 4-hydroxyphenylpyruvate.

Reaction


In enzymology, a prephenate dehydrogenase is an enzyme that catalyzes the chemical reaction
 * prephenate + NAD+ $$\rightleftharpoons$$ 4-hydroxyphenylpyruvate + CO2 + NADH

Thus, the two substrates of this enzyme are prephenate and NAD+, whereas its 3 products are 4-hydroxyphenylpyruvate, CO2, and NADH.

Structure
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-CH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is prephenate:NAD+ oxidoreductase (decarboxylating). Other names in common use include hydroxyphenylpyruvate synthase, and chorismate mutase---prephenate dehydrogenase. This enzyme participates in phenylalanine, tyrosine and tryptophan biosynthesis and novobiocin biosynthesis.

Also found in haemophilus influenzae, synechocystis (bacteria), and aquifex aeolicus (plant).

However, in haemophilus influenzae, prephenate dehydrogenase is fused with the enzyme chorismate mutase. This fusion is not found in plants or animals.

Structural studies
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes and.