Alteration of enzymes in ageing human fibroblasts in culture. IV. Effect of glutathione on the alteration of glucose-6-phosphate dehydrogenase.
Alteration and inactivation of glucose-6-phosphate dehydrogenase (G6PD) can be induced in human fibroblasts by incubation of a cell supernatant at 4 degrees C and pH 7.4. When added in such conditions, glutathione (GSH) had a stabilizing effect on the enzyme. On the other hand, substances which are known to deplete the cells of their GSH content, dramatically increase the inactivation rate. When analysed by gel filtration after 24 h of incubation at 4 degrees C, the inactive G6PD appears as a dimeric protein when GSH is present, while as a monomer in the control experiment. Reactivation of the monomers was stimulated with GSH. The heat inactivation of the dimeric fraction first started with a sharp activity increase of 20%. This increase vanished when the enzyme was first reactivated before the thermolability experiment. We propose that what is called altered G6PD is the expression of a quick reactivation of an inactive, labile dimer. Finally, a schematic view of the G6PD alteration is proposed.
D002460:Cell Line; D005347:Fibroblasts / Q000201:enzymology; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D005978:Glutathione / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D008168:Lung; D013997:Time Factors
D005954:Glucosephosphate Dehydrogenase; D005978:Glutathione