Effect of L-penicillamine hydantoin, an analogue of glutathione, on rat liver glutathione peroxidase, reductase and transferase reactions.
In soluble fractions prepared from rat liver homogenates, L-penicillamine hydantoin appeared to be, on the basis of SH consumption measurements, a substrate for glutathione peroxidase but not transferase reactions. When glutathione is incubated with rat liver soluble proteins in the presence of penicillamine hydantoin, formation of oxidized glutathione is inhibited. Calculations from Lineweaver-Burk plots point out that inhibition by L-penicillamine hydantoin of the peroxide-dependent oxidations of glutathione is mixed, since both apparent Km and Vmax values are modified. Preincubation of rat liver soluble proteins with L-penicillamine hydantoin led to a progressive inactivation of glutathione peroxidase. The kinetics of this inactivation process with respect to time and inactivator concentration were studied. Inclusion in the preincubation mixture of SH-containing molecules such as dithiothreitol, L-cysteine or glutathione protected the enzyme against inactivation. However, none of these molecules and neither hydantoin, Triton X-100, phenol, nor dialysis could reverse the enzyme from inactivated to activated form. Mitochondrial glutathione peroxidase was inhibited and inactivated by L-penicillamine hydantoin to the same extent as its cytosolic counterpart. Modifications by penicillamine hydantoin of various subcellular markers enzymes (lactate dehydrogenase, N-acetyl beta-glucosaminidase, arylsulfatase C, butyryl-CoA dehydrogenase, lauryl-CoA and glycolate oxidases) were of weak amplitude consisting of either inhibition, inactivation or stimulation.
Mestdagh
N
N
Unité INSERM U 16, Lille, France.
Poupaert
J
J
Hénichart
J P
JP
Vamecq
J
J
D000818:Animals; D005978:Glutathione / Q000031:analogs & derivatives* / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000037:antagonists & inhibitors*; D005980:Glutathione Reductase / Q000037:antagonists & inhibitors*; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors*; D006827:Hydantoins / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D010396:Penicillamine / Q000031:analogs & derivatives*; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000187:drug effects; D013379:Substrate Specificity
D006827:Hydantoins; D006861:Hydrogen Peroxide; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase; D005982:Glutathione Transferase; D005978:Glutathione; D010396:Penicillamine