Effect of Sulfhydryl Group Modification on Erythrocyte Membrane Adenosine Triphosphatase ∗

Summary

When intact human erythrocytes were treated with DTNB, about 5% of total membrane sulfhydryl groups were modified. No detectable changes were observed in the ATPase of the membrane fragments prepared from DTNB-treated cells. However, when membrane fragments were reacted directly with DTNB, about 50% of total sulfhydryl groups were modified and the (Na + K)-activated ATPase was completely abolished, while cation-independent ATP ase remained unchanged. About 80% of the (Na + K)-activation could be recovered by removing the sulfhydryl modifying groups with DTT.