Characterization of Plasmodium berghei glutathione synthetase.

Plasmodium berghei contained 0.454±0.031 U/mg of glutathione synthetyase (GS). GS was purified using solid ammonium sulfate and Sephadex G-200 from P. berghei infected mouse erythrocytes. SDS-PAGE showed purified GS as a single band protein of 70 kDa and its Km for γ-glutamylcysteine, glycine and ATP being 0.33 mM, 8.3 mM and 0.43 mM respectively with noncompetitive inhibition by GSH. The malaria parasite enzyme was optimally active at 37°C and pH 8.0-8.5. Heavy metals significantly inhibited parasite GS activity.