A novel dinitrophenylglutathione-stimulated ATPase is present in human erythrocyte membranes.

Vesicles prepared from human erythrocyte membranes were found to catalyze ATP hydrolysis that was stimulated by dinitrophenylglutathione (Dnp-SG). This activity was dependent on temperature and Mg2+ and independent of ion pump ATPases present in erythrocyte membranes. The activity was a linear function of protein and time up to 60 min. The Km values of ATPase for Dnp-SG and ATP were found to be 49 microM and 1.67 mM, respectively. This suggests that in erythrocytes, the transport of Dnp-SG requires direct enzymatic hydrolysis of ATP and both Dnp-SG-stimulated ATPase activity and the ATP-dependent efflux of Dnp-SG from erythrocytes represent different activities of the same protein.