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pubmed:abstractText |
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 (lambda) by the first procedure had 4 subunits (alpha, beta, gamma, and epsilon). It did not bind to a deficient membrane, nor did it reconstitute ATP-driven transhydrogenase activity. Our modified procedure (b) yielded 5 subunits (alpha, beta, gamma, delta, and epsilon). This ATPase could bind to a deficient membrane and reconstitute ATP-driven transhydrogenase. This finding suggests that the delta 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.
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