On the H+/2e- stoichiometry of the respiratory chain

Guadalupe Guerra, Federico Martínez, Juan Pablo Pardo

Research output: Contribution to journalReview articlepeer-review

7 Scopus citations


To calculate the number of ATP molecules synthesized during oxidative phosphorylation, and to understand the yield and efficiency of this process, it is necessary to know the H+/2e- stoichiometry of the respiratory complexes, as well as the H+/ATP ratio for the ATP synthase. However, in most biochemistry textbooks, this topic is treated poorly. For example, several books simply mention that mitochondrial respiratory complexes pump protons across the membrane, without any reference to the number of protons translocated per pair of electrons [1-4]. Stryer's textbook [5] mentions a 4H+/2e-, 2H+/2e-, 4H +/2e- stoichiometry for complex I, III, and IV, respectively, but most recent editions of the biochemistry textbooks of Nelson and Cox [6] and Voet et al. [7] cite a 4, 4, 2 stoichiometry [6, 7]. Several years ago Hinkle et al. [8] proposed a 4, 2, 4 stoichiometry for the "effective" pumping of protons across the membrane; interestingly, these values are identical to the number of charges moved across the inner mitochondrial membrane by respiratory complexes I, III, and IV. The present work describes several arguments in favor of the stoichiometry of 4, 2, 4 for complex I, III, and IV, respectively.

Original languageEnglish
Pages (from-to)363-367
Number of pages5
JournalBiochemistry and Molecular Biology Education
Issue number6
StatePublished - Nov 2002


  • ATP synthesis
  • Complex I
  • Complex III
  • Complex IV
  • H /2e stoichiometry
  • Mitochondrial respiratory chain
  • Proton pumping


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