Assay, properties and tissue distribution of p-hydroxyphenylpyruvate hydroxylase

Four-Hydroxyphenylpyruvic Acid Oxidase Deficiency with Normal Fumarylacetoacetase: a New Variant Form of Hereditary Hypertyrosinemia

“…al. (12) reported that the activity of pHPP oxidase in the human fetal liver and kidney was undetectable at least until 28 wk of gestational age; thus, maternal hypertyrosinemia and fetal pHPP oxidase deficiency, especially in the early or midfetal life of the fetus, might have no adverse effects on intrauterine development. On the other hand, the adverse effects of hypertyrosinemia had been observed in transient hypertyrosinemia of newborns (26), although these effects were diminished with the reduction o f blood tyrosine level (26).…”

Inhibition of Barnyardgrass 4-Hydroxyphenylpyruvate Dioxygenase by Sulcotrione

“…Examples of K, values for HPPD extracted from other organisms are 30 PM for human liver (Lindblad et al, 1977), 20 to 50 PM for rat liver (Lin et al, 1958;Fellman et al, 1972), and 30 m for Pseudomonas . The K, of the frog liver HPPD was originally reported to be 500 I.IM (Laskowska-Klita, 1969), but more recent results indicate that the value is 50 PM (Lindstedt et al, 1982).…”

Letter to the Editor: Reply to Dr. Buist

“…The so-called substrate inhibition is-a contrivance of the enzyme assay in which oxygen inactivation of the enzyme occurs in the presence of the ketoacid. At physiologic PO, no inhibition is observed (5). The urinary metabolite patterns and the different handling of a tyrosine load in the two patients could just as well be explained by a difference in the amount of residual cytosol tyrosine aminotransferase activity.…”