Figure 1.

Cleavage of Na,K-ATPase mediated by ATP–Fe²⁺ or AMP-PNP–Fe²⁺ complexes. The enzyme was suspended in the medium containing 300 mM choline chloride, or other salts as indicated, and incubated with 5 mM ascorbate/H₂O₂, 5 μM FeSO₄ as follows. (A) In lanes designated Cont. Rb and Cont. choline, ATP was omitted; in the other lanes, 30 μM ATP or AMP-PNP were added (5 min incubation); (B) ATP as indicated, 4 min incubation; (C) 166 μM ATP, MgCl₂ as indicated, 5 min incubation; (D) 500 μM ATP, 10 min incubation; (E) 500 μM ATP, 30 min incubation.