Effect of lead concentration on the level of glutathione, glutathione S-transferase, reductase and peroxidase in human blood.

Incubation of human whole blood for 24 h at 37 degrees C in the presence of 100-400 microg/dl lead chloride or lead acetate caused a concentration-dependent decrease in the level of reduced glutathione up to 40%. Similarly, the activities of glutathione reductase, glutathione peroxidase and glutathione S-transferase were decreased up to 25%, 50%, and 19%, respectively. Moreover, 100 microg/dl lead chloride or lead acetate slowed the process of glutathione regeneration, and delayed the time for complete regeneration from 20 to 40 min. When glutathione S-transferase was purified by affinity chromatography on Sepharose-linked glutathione, incubated with lead chloride or lead acetate, a concentration-dependent inhibition of the enzymatic activity was observed reaching 50% inhibition at a lead salt concentration of 6000 microg/dl.