title: Enzyme defect in a case of tyrosinemia type I, acute form.
abstract: We determined the activities of tyrosine aminotransferase (TAT, EC 2.6.1.5), p-hydroxyphenylpyruvate oxidase (p- HPPA oxidase, EC 1.14.2.2) and fumarylacetoacetate fumarylhydrolase ( FAH , EC 3.7.12) in cytosol of the liver and kidney tissues obtained at autopsy from a case of hereditary tyrosinemia type I. Values were compared with those from a control group of autopsied tissues from three adults and six children, who had died of other causes. In tyrosinemia, these three hepatic enzyme activities were all decreased: TAT showed approximately 35%, p- HPPA oxidase 11%, and FAH 60% of the corresponding control values. On the other hand, kidney enzymes in tyrosinemia revealed that FAH was most significantly decreased to approximately 14% of the control activity. Km values for substrate--determined for p- HPPA oxidase and FAH --were not different between the patient and controls, suggesting no altered properties of these enzymes. We conclude that in the present case of hereditary tyrosinemia type I, the activities of p- HPPA oxidase in liver and FAH in kidney were most strikingly affected. This fact may in part explain the deteriorated metabolism of tyrosine observed in this patient.
mesh_terms: D015111:4-Hydroxyphenylpyruvate Dioxygenase / Q000172:deficiency*; D000592:Amino Acid Metabolism, Inborn Errors / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D006801:Humans; D006867:Hydrolases / Q000172:deficiency*; D007231:Infant, Newborn; D007668:Kidney / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D008297:Male; D010105:Oxygenases / Q000172:deficiency*; D014443:Tyrosine / Q000097:blood* / Q000378:metabolism; D014444:Tyrosine Transaminase / Q000172:deficiency*
chemical_list: D014443:Tyrosine; D010105:Oxygenases; D015111:4-Hydroxyphenylpyruvate Dioxygenase; D014444:Tyrosine Transaminase; D006867:Hydrolases; C020156:fumarylacetoacetase