title: L-Ornithine-ketoacid-transaminase deficiency in cultured fibroblasts of a patient with hyperornithinaemia and gyrate atrophy of the choroid and retina.
abstract: L-Ornithine-ketoacid-transaminase deficiency was established in cultured fibroblasts obtained from a patient with hyperornithinaemia (mean ornithine level in serum approximately 100 mumol/l) and gyrate atrophy of the choroid and retina. The deficiency was found both the L-ornithine concentrations of 3.0 mM (about twice the KM value) and 12 mM, indicating that the enzymic defect was not due to a decreased affinity for this substrate. The reliability of the colorimetric assay of ornithine-ketoacid-transaminase activity was established radiochemically. Performance of the radiochemical assay revealed the presence of an impurity in the substrate DL-[2-14C]ornithine - HCl being a strong inhibitor of the enzyme. The passage level and the subcultivation time of the fibroblasts did not influence the enzymic activity.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D001284:Atrophy / Q000201:enzymology; D002478:Cells, Cultured; D002648:Child; D002829:Choroid / Q000473:pathology*; D005260:Female; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans; D066298:In Vitro Techniques; D009952:Ornithine / Q000097:blood*; D009953:Ornithine-Oxo-Acid Transaminase / Q000172:deficiency*; D012160:Retina / Q000473:pathology; D012164:Retinal Diseases / Q000150:complications / Q000201:enzymology*; D013997:Time Factors; D000637:Transaminases / Q000172:deficiency*; D014603:Uveal Diseases / Q000150:complications / Q000201:enzymology
chemical_list: D000596:Amino Acids; D009952:Ornithine; D000637:Transaminases; D009953:Ornithine-Oxo-Acid Transaminase