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Normally, the breakdown of the amino acid tyrosine involves the conversion of 4-hydroxyphenylpyruvate to homogentisate by 4-hydroxyphenylpyruvate dioxygenase. Complete deficiency of this enzyme would lead to tyrosinemia III. In rare cases, however, the enzyme is still able to produce the reactive intermediate 1,2-epoxyphenyl acetic acid, but is ...
Tyrosinemia type III is a rare disorder caused by a deficiency of the enzyme 4-hydroxyphenylpyruvate dioxygenase (EC 1.13.11.27), encoded by the gene HPD. [2] This enzyme is abundant in the liver, and smaller amounts are found in the kidneys. It is one of a series of enzymes needed to break down tyrosine.
HPPD also catalyzes the conversion of phenylpyruvate to 2-hydroxyphenylacetate and the conversion of α-ketoisocaproate to β-hydroxy β-methylbutyrate. [2] [3] HPPD is an enzyme that is found in nearly all aerobic forms of life. [4] This reaction shows the conversion of 4-hydroxyphenylpyruvate into homogentisate by HPPD.
4-Hydroxyphenylpyruvic acid (4-HPPA) is an intermediate in the metabolism of the amino acid phenylalanine. The aromatic side chain of phenylalanine is hydroxylated by the enzyme phenylalanine hydroxylase to form tyrosine. The conversion from tyrosine to 4-HPPA is in turn catalyzed by tyrosine aminotransferase. [2]
The United States Food and Drugs Administration is warning pet owners about a common medication given to pets to treat arthritis. The F.D.A. now says that the drug Librela may be associated with ...
4-Hydroxyphenylpyruvate dioxygenase (HPPD) is an enzyme found in both plants and animals, which catalyzes the catabolism of the amino acid tyrosine. [4] Preventing the breakdown of tyrosine has three negative consequences: the excess of tyrosine stunts growth; the plant suffers oxidative damage due to lack of tocopherols (vitamin E); and ...
Aromatic-ring-hydroxylating dioxygenases (ARHD) incorporate two atoms of dioxygen (O 2) into their substrates in the dihydroxylation reaction.The product is (substituted) cis-1,2-dihydroxycyclohexadiene, which is subsequently converted to (substituted) benzene glycol by a cis-diol dehydrogenase.
In enzymology, a 4-hydroxyphenylpyruvate oxidase (EC 1.2.3.13) is an enzyme that catalyzes the chemical reaction. 4-hydroxyphenylpyruvate + 1/2 O 2 4-hydroxyphenylacetate + CO 2. Thus, the two substrates of this enzyme are 4-hydroxyphenylpyruvate and O 2, whereas its two products are 4-hydroxyphenylacetate and CO 2.