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B6db references: 81216001

type Journal Article
authors Sipila, I.; Simell, O.; O'Donnell, J. J.
title Gyrate atrophy of the choroid and retina with hyperornithinemia: characterization of mutant liver L-ornithine:2-oxoacid aminotransferase kinetics
journal J Clin Invest
ui 81216001
year (1981)
volume 67
number 6
pages 1805-7.
keywords Adult
abstract Deficient activity of L-ornithine:2-oxoacid aminotransferase is associated with gyrate atrophy of the choroid and retina with hyperornithinemia, an autosomal recessive disease leading to blindness. Liver tissue from two patients contained trace activity of the enzyme. The Michaelis (Km) value of the mutant enzyme for ornithine was 200 mM, 50-fold higher than normal, but increasing the concentrations of alpha- oxoglutarate and pyridoxal 5'-phosphate to 10 times those giving maximal activity of the normal enzyme had no effect on the mutant enzyme. Substrate inhibition of the mutant could not be demonstrated at 1,000 mM ornithine concentration, whereas ornithine concentrations above 70 mM inhibited the normal enzyme. The data suggest that the abnormal L-ornithine:2-oxoacid aminotransferase in the two patients studied has an altered binding site for ornithine.
last changed 2002/11/04 17:41

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