4-Hydroxyphenylpyruvic acid (4-HPPA) is an intermediate in the metabolism of the amino acid

phenylalanine Phenylalanine (symbol Phe or F) is an essential α-amino acid with the chemical formula, formula . It can be viewed as a benzyl group substituent, substituted for the methyl group of alanine, or a phenyl group in place of a terminal hydrogen of ...

. The aromatic side chain of phenylalanine is hydroxylated by the enzyme

phenylalanine hydroxylase Phenylalanine hydroxylase (PAH) () is an enzyme that catalyzes the hydroxylation of the aromatic side-chain of phenylalanine to generate tyrosine. PAH is one of three members of the biopterin-dependent aromatic amino acid hydroxylases, a clas ...

to form

tyrosine -Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a conditionally essential amino acid with a polar side group. The word "tyrosine" is ...

. The conversion from tyrosine to 4-HPPA is in turn catalyzed by

tyrosine aminotransferase Tyrosine aminotransferase (or tyrosine transaminase) is an enzyme present in the liver and catalyzes the conversion of tyrosine to 4-hydroxyphenylpyruvate. L-tyrosine + 2-oxoglutarate \rightleftharpoons 4-hydroxyphenylpyruvate + L-glutama ...

. Additionally, 4-HPPA can be converted to

homogentisic acid Homogentisic acid (2,5-dihydroxyphenylacetic acid) is a phenolic acid usually found in ''Arbutus unedo'' (strawberry-tree) honey. It is also present in the bacterial plant pathogen ''Xanthomonas campestris'' pv. ''phaseoli'' as well as in the ye ...

which is one of the precursors to ochronotic pigment. It is an intermediary compound in the biosynthesis of scytonemin.

References

{{DEFAULTSORT:Hydroxyphenylpyruvic acid Natural phenols Alpha-keto acids Propionic acids Hydroxy acids

See also

References