ATP synthesis driven by a protonmotive force in Streptococcus lactis

Peter C. Maloney, T. Hastings Wilson

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


An electrochemical potential difference for hydrogen ions (a protonmotive force) was artificially imposed across the membrane of the anaerobic bacterium Streptococcus lactis. When cells were exposed to the ionophore, valinomycin, the electrical gradient was established by a potassium diffusion potential. A chemical gradient of protons was established by manipulating the transmembrane pH gradient. When the protonmotive force attained a value of 215 mV or greater, net ATP synthesis was catalyzed by the membrane-bound Ca++, Mg++-stimulated ATPase. This was true whether the protonmotive force was dominated by the membrane potential (negative inside) or the pH gradient (alkaline inside). Under these conditions, ATP synthesis could be blocked by the ATPase inhibitor, dicyclohexylcarbodiimide, or by ionophores which rendered the membrane specifically permeable to protons. These observations provide strong evidence in support of the chemiosmotic hypothesis, which states that the membrane-bound ATPase couples the inward movement of protons to the synthesis of ATP.

Original languageEnglish (US)
Pages (from-to)285-310
Number of pages26
JournalThe Journal of Membrane Biology
Issue number1
StatePublished - Dec 1 1975

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology


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