CELL AGE-DEPENDENT DECAY OF HUMAN ERYTHROCYTES GLUTATHIONE-S-TRANSFERASE

Human red blood cells contain both glutathione S-transferase-sigma (GST-sigma) and glutathione S-transferase-rho (GST-rho). While the first isozyme does not change in red blood cell fractions of different mean density (age), GST-rho, the main isozyme, shows a pronounced cell age dependent decay. Ion-exchange chromatographic experiments show that GST-rho consists of only one isozymic form in young erythrocytes but is present in two components, with different electric charge, in mature and old cells. The "secondary" GST-rho isozyme is more heat stable than the "primary" GST-rho isozyme with the result that the total GST activity shows an apparent increase in heat stability during cell aging due to the formation of "secondary" isozymes. The kinetic properties and specificity of this enzyme do not show appreciable modifications during cell ageing. The data reported in this paper suggest that red blood cell aging is associated with a reduced detoxifying ability due to GST-rho decay.