Effect of inhibitors of protein synthesis on the formation of phenols derived from acetate and shikimic acid in Aspergillus fumigatus.
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A Japanese girl, 2 years, 8 months of age, with palmoplantar keratosis and dendritic corneal opacities, showed increased tyrosine levels in the plasma, urine, and cerebrospinal fluid. The mental and physical growth was not retarded. The hepatorenal functions were within normal limits. Electron microscopically, the epidermal keratinocytes showed increased tonofibrils and no structures suggestive of tyrosine crystals. Cytosol and mitochondrial tyrosine aminotransferase (TAT) activities of the liver were greatly decreased, while p-hydroxyphenyl pyruvate oxidase (p-HPPO) activity was not decreased. The plasma tyrosine levels were controlled for 3 years with low phenylalanine-tyrosine diet.
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trans-2'-Carboxybenzalpyruvate hydratase-aldolase was purified from a phenanthrene-degrading bacterium, Nocardioides sp. strain KP7, and characterized. The purified enzyme was found to have molecular masses of 38 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 113 kDa by gel filtration chromatography. Thus, the homotrimer of the 38-kDa subunit constituted an active enzyme. The Km and kcat values of this enzyme for trans-2'-carboxybenzalpyruvate were 50 microM and 13 s(-1), respectively. trans-2'-Carboxybenzalpyruvate was transformed to 2-carboxybenzaldehyde and pyruvate by the action of this enzyme. The structural gene for this enzyme was cloned and sequenced; the length of this gene was 996 bp. The deduced amino acid sequence of this enzyme exhibited homology to those of trans-2'-hydroxybenzalpyruvate hydratase-aldolases from Pseudomonas putida PpG7 and Pseudomonas sp. strain C18.
Enzymatic studies on the liver of an infant are described-a case of hypertyrosinemia without hepatic dysfunction. His parents were siblings and the mother had hypertyrosinemia. Excessive amounts of 4-hydroxyphenylpyruvic acid (pHPP), 4-hydroxyphenylacetic acid (pHPL), and 4-hydroxyphenylacetic acid (pHPA) were found to be excreted in the patient's urine as well as in the urine of the mother and the inhibitor of porphobilinogen synthetase was not found. Soluble tyrosine aminotransferase (s-TAT), separated from that of the mitochondrial form (m-TAT) by DE 52 column chromatography, was normal in the patient's liver, both quantitatively and qualitatively. The activities of fumarylacetoacetase in the patient's liver and in the peripheral leucocytes from the parents were normal. The activity of pHPP oxidase in the patient's liver was approximately 5% of the control and the enzyme had a high Km value for pHPP (controls: 0.06 +/- 0.01 mM, patient: 0.23 +/- 0.03 mM). From these results, the patient was thought to be different from previously described types of tyrosinemia and perhaps representative of a new variant form. This is the first report concerning 4-hydroxyphenylpyruvic acid oxidase deficiency alone. Mild metal retardation and mild hypertyrosinemia may be offered as typical clinical features of the disease.
Phenylalanine in conjunction with p-chlorophenylalanine or alpha-methylphenylalanine was administered to suckling rats to induce hyperphenylalaninemia reminiscent of untreated phenylketonuria, and developmental parameters were monitored. The experimental model utilizing p-chlorophenylalanine was found to be unsatisfactory, in that the drug had general deleterious effects on growth, numerous side effects including increased mortality, and affected brain levels of biogenic monoamine neurotransmitters. The model utilizing alpha-methylphenylalanine was relatively free from nonspecific effects and thus, changes observed in the animals were attributable to experimental phenylketonuria. The latter animals had slightly decreased body and brain weights, and exhibited grossly elevated serum phenylalanine and urinary excretion of phenylketone metabolites. Hyperphenylalaninemia produced greatly disrupted brain amino acids at 10 days of age (prior to the formalization of the blood-brain barrier and specific transport systems) which was limited by 30 days of age to changes in glycine, gamma-aminobutyric acid and the aliphatic and aromatic amino acids which compete for uptake in the brain by a common carrier. These animals also exhibited a myelin deficit and changes in proteins from isolated nerve cell preparations. Mature animals which had daily treatment up to 60 days of age exhibited a long-term learning impairment. These observations are consistent with many aspects of the clinical picture of untreated phenylketonuric patients, and suggest that this animal model will be beneficial in studying the disease.
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