Low molecular weight thiol content in glutathione synthetase-deficient human fibroblasts.
The activity and the kinetic properties of glutathione synthetase and the concentrations of non-protein bound thiols of the gamma-glutamyl cycle were measured in 11 human fibroblast cell strains. Six of these strains were derived from patients suffering from 5-oxoprolinuria, a recessive genetic disease characterized by a deficiency in glutathione synthetase; the other cell strains were derived from healthy heterozygous or homozygous relatives of the patients. The glutathione synthetase activities of homozygous deficient strains were 1/3 of control values while those of heterozygous strains were 2/3 of control values. The total thiol concentration was lower in only 3 of the 6 deficient homozygotes and that of glutathione (GSH) was lower in only 4 of the 6 deficient homozygotes. This lower GSH level was at least partly offset by an accumulation of gamma-glutamylcysteine, a precursor of GSH, which is almost completely absent from control cells. The total quantities of thiols and GSH in plateau phase cells were about 50% and 30% respectively of the levels in growth phase cells. Approximately 80% of the GSH was in the reduced form in both quiescent and growing cells.
Debieu
D
D
Laboratoire de Radiobiologie Cellulaire, Unité INSERM 247, Institut Gustave-Roussy, Villejuif, France.
Deschavanne
P J
PJ
Malaise
E P
EP
D004151:Dipeptides / Q000378:metabolism; D005347:Fibroblasts / Q000032:analysis* / Q000201:enzymology; D005981:Glutathione Synthase / Q000172:deficiency*; D005998:Glycine / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008970:Molecular Weight; D010453:Peptide Synthases / Q000172:deficiency*; D013438:Sulfhydryl Compounds / Q000032:analysis*
D004151:Dipeptides; D013438:Sulfhydryl Compounds; C042262:gamma-glutamyl-alpha-aminobutyrate; D010453:Peptide Synthases; D005981:Glutathione Synthase; D005998:Glycine