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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.
[1] [2] 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 ...
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]
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 ...
Biosynthesis of HPG. HPG is synthesized from prephenate, an intermediate in the shikimic acid pathway and also a precursor to tyrosine.Prephenate is aromatized by prephenate dehydrogenase (Pdh) using NAD + as a cofactor to produce 4-hydroxyphenylpyruvate. 4-Hydroxyphenylpyruvate is then oxidized by 4-hydroxymandelate synthase (4HmaS) using oxygen to form 4-hydroxymandelate and hydrogen ...
The oxygen incorporated need not be derived from O 2. The systematic name of this enzyme class is 3,4-dihydroxyphenylacetate:oxygen 2,3-oxidoreductase (decyclizing). Other names in common use include 3,4-dihydroxyphenylacetic acid 2,3-dioxygenase, HPC dioxygenase, and homoprotocatechuate 2,3-dioxygenase.
The molecular formula C 9 H 8 O 4 (molar mass: 180.15 g/mol, exact mass: 180.0423 u) may refer to: Acetozone; Aspirin; 4-Hydroxyphenylpyruvic acid, a natural phenol; Dihydroxycinnamic acids: Caffeic acid (3,4-Dihydroxycinnamic acid) Umbellic acid (2,4-dihydroxycinnamic acid) 2,3-Dihydroxycinnamic acid; 2,5-Dihydroxycinnamic acid; 3,5 ...