4-Hydroxyphenylpyruvate dioxygenase

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4-hydroxyphenylpyruvate dioxygenase
Identifiers
Symbol	HPD PPD;
HUGO	5147
Entrez	3242
OMIM	609695
RefSeq	NM_002150
UniProt	P32754
Other data
EC number	1.13.11.27
Locus	Chr. 12 q24-qter

4-Hydroxyphenylpyruvate dioxygenase HPD is a Cu-containing enzyme, that catalyzes the third reaction in the catabolism of phenylalanine and tyrosine - the conversion of 4-hydroxyphenylpyruvate to homogentisate.

[edit] Function

The HPD reaction occurs through a NIH shift and involves the oxidative decarboxylation of an α-oxo acid as well as aromatic ring hydroxylation. The NIH-shift, which has been demonstrated through isotope-labeling studies, involves migration of an alkyl group to form a more stable carbocation. The shift, accounts for the observation that C3 is bonded to C4 in 4-hydroxyphenylpyruvate but to C5 in homogentisate.