The Mg 2+ - and Ca 2+ -stimulated ATPase (EC 3.6.1.3; ATP phosphohydrolase) (bacterial coupling factor) was purified from two strains of E. coli by two different procedures: ( a ) method of Nelson, Kanner, and Gutnick [ Proc. Nat. Acad. Sci. USA (1974) 71, 2720-2724] and ( b ) a modified procedure described in this paper. The ATPase purified from E. coli K12 (λ) by the first procedure had 4 subunits (α, β, γ, and ε). It did not bind to a deficient membrane, nor did it reconstitute ATP-driven transhydrogenase activity. Our modified procedure ( b ) yielded 5 subunits (α, β, γ, δ, and ε). This ATPase could bind to a deficient membrane and reconstitute ATP-driven transhydrogenase. This finding suggests that the δ subunit is required for the reaction with the membrane. The molecular weight of the 4-subunit ATPase was significantly lower than that of the 5-subunit ATPase, as judged by equilibrium centrifugation. The specific ATPase activities of both preparations were about the same. These two procedures were also applied to E. coli ML308-225.

Futai, M., Sternweis, P. C., & Heppel, L. A. (1974). Purification and Properties of Reconstitutively Active and Inactive Adenosinetriphosphatase from Escherichia coli. Proceedings of the National Academy of Sciences, 71(7), 2725–2729.