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4-Hydroxyphenylpyruvate dioxygenase (HPPD), also known as α-ketoisocaproate dioxygenase (KIC dioxygenase), is an Fe(II)-containing non-heme oxygenase that catalyzes the second reaction in the catabolism of tyrosine - the conversion of 4-hydroxyphenylpyruvate into homogentisate.
The mechanism of action of nitisinone involves inhibition of 4-Hydroxyphenylpyruvate dioxygenase (HPPD). [5] [6] This is a treatment for patients with Tyrosinemia type 1 as it prevents the formation of 4-Maleylacetoacetic acid and fumarylacetoacetic acid, which have the potential to be converted to succinyl acetone, a toxin that damages the liver and kidneys. [4]
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 ...
Several hydroxylase enzymes are believed to incorporate an NIH shift in their mechanism, including 4-hydroxyphenylpyruvate dioxygenase and the tetrahydrobiopterin dependent hydroxylases. The name NIH shift arises from the US National Institutes of Health from where studies first reported observing this transformation.
In 1965, doubts emerged that the underlying biochemical cause of hepatorenal tyrosinemia was a defective form of the 4-hydroxyphenylpyruvate dioxygenase enzyme. In 1977, Bengt Lindblad and colleagues at the University of Gothenburg in Sweden demonstrated that the actual defect in causing hepatorenal tyrosinemia involved the fumarylacetoacetate ...
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 ...
L-tyrosine + 2-oxoglutarate 4-hydroxyphenylpyruvate + L-glutamate In humans, the tyrosine aminotransferase protein is encoded by the TAT gene . [ 7 ] A deficiency of the enzyme in humans can result in what is known as type II tyrosinemia , wherein there is an abundance of tyrosine as a result of tyrosine failing to undergo an aminotransferase ...
4-Hydroxyphenylpyruvate (produced by transamination of tyrosine) is acted upon by the enzyme 4-hydroxyphenylpyruvate dioxygenase to yield homogentisate. [5] If active and present, the enzyme homogentisate 1,2-dioxygenase further degrades homogentisic acid to yield 4-maleylacetoacetic acid. [6]