A Soluble Mitochondrial ATP Synthetase Complex Catalyzing ATP-Phosphate and ATP-ADP Exchange

  1. Robert J. Fisher,
  2. Jenn C. Chen,
  3. B. P. Sani,
  4. Suresh S. Kaplay, and
  5. D. Rao Sanadi*,*
  1. *Boston Biomedical Research Institute, Department of Cell Physiology, 20 Staniford Street, Boston, Mass. 02114
  2. Department of Biological Chemistry, Harvard Medical School, Boston, Mass. 02115

Abstract

The highly purified soluble ATP synthetase complex from mitochondria, containing energy-transfer Factor A (the terminal ADP phosphorylation enzyme of oxidative phosphorylation) and Factor D, catalyzes ATP-Pi and ATP-ADP exchange reactions. The ATP-Pi exchange activity is inhibited by low concentrations of the uncouplers of oxidative phosphorylation, oligomycin and p-chloromercnriphenylsulfonate. It is stimulated threefold by dithiothreitol and is Mg++ dependent. Antiserum to coupling factor 1 (F1) also inhibits the ATP-Pi exchange. The ATP-ADP exchange activity appears to be greater than the ATP-Pi exchange activity. The results suggest that the nonphosphorylated high-energy intermediate (X∼C), and possibly the phosphorylated intermediate (X∼P), are formed on the synthetase. Sites of uncoupler and oligomycin action reside in the terminal ATP synthetase.

Footnotes

  • ↵ * Send reprint requests to Dr. Sanadi.

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  1. PNAS September 1, 1971 vol. 68 no. 9 2181-2184
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