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The first two steps in the mammalian lysine-degradation pathway are catalyzed by lysine-ketoglutarate reductase and saccharopine dehydrogenase, respectively, resulting in the conversion of lysine to alpha-aminoadipic semialdehyde. Defects in one or both of these activities result in familial hyperlysinemia, an autosomal recessive condition characterized by(More)
Familial hyperlysinemias are autosomal recessive disorders in the oxidative degradation of lysine. Hyperlysinemia type I is associated with a combined deficiency in lysine-ketoglutarate reductase and saccharopine dehydrogenase activities, the first two sequential steps in the lysine degradative pathway. In familial hyperlysinemia type II, only saccharopine(More)
The term molecular chaperone includes a large family of unrelated proteins that comprise both stress-inducible and constitutive molecules. In recent years, molecular chaperones or heat-shock proteins (Hsps) have emerged as fundamentally important topics in cell biology. Living organisms respond to stressful conditions, such as heat shock, by rapidly(More)
To detect heterozygotes for maple-syrup-urine disease (MSUD), activities of branched-chain-alpha-ketoacid (BCKA) dehydrogenase and its components in skin fibroblasts of two obligatory heterozygotes and amnion cells of a fetus at risk were measured. Intact heterozygous cells were found to decarboxylate [1-14C] alpha-ketoisovalerate at rates equal to or only(More)
Fibroblasts grown in tissue culture from the skin of normal subjects have lysine-ketoglutarate reductase activity (lysine: alpha-ketoglutarate: triphosphopyridine nucleotide (TPNH) oxidoreductase (epsilon-N-[L-glutaryl-2]-L-lysine forming)). The activity of the enzyme is considerably reduced in the skin fibroblasts grown from three siblings with(More)
The Hermansky-Pudlak syndrome consists of tyrosine-positive albinism, a defect in the second phase of platelet aggregation, and widespread accumulation of a ceroidlike pigment in tissue. Pulmonary fibrosis has also been reported. In this paper, we describe two families with documented Hermansky-Pudlak syndrome in which four members, two from each family,(More)
We have identified two novel mutant alleles in the transacylase (E2) gene of the human branched-chain alpha-keto acid dehydrogenase (BCKAD) complex in 6 of 38 patients with maple syrup urine disease (MSUD). One mutation, a 2-bp (AT) deletion in exon 2 of the E2 gene, causes a frameshift downstream of residue (-26) in the mitochondrial targeting presequence.(More)
Discordance between clinical phenotype and the level of a mutant enzyme activity may reflect differences between enzyme function in vivo and that measured by the customary enzyme assays on cell extracts. In the present study, the conversion of hypoxanthine to phosphorylated products was measured in intact skin fibroblasts and in cell extracts from seven(More)