A novel dinitrophenylglutathione‐stimulated ATPase is present in human erythrocyte membranes

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Abstract
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 Me2+ 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 K m values of ATPase for Dnp‐SG and ATP were found to be 49 μM 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.