Template:Correction NAD and H+

Hydrogen ion ambiguities in the electron transfer system

Communicated by Gnaiger E (2023-10-04)

Electron (e^-) transfer linked to hydrogen ion (H⁺) transfer is a fundamental concept in the field of bioenergetics, critical for understanding redox-coupled energy transformations. However, the current literature contains ambiguities regarding H⁺ formation on the negative side of bioenergetic membranes, such as the matrix side of the mitochondrial inner membrane, during oxidative phosphorylation (OXPHOS). This uncertainty arises particularly when examining the oxidation of NADH by respiratory Complex I or succinate by Complex II. The graphical representations depicting putative H⁺ formation in these redox reactions conflict with chemiosmotic coupling stoichiometries between H⁺ translocation across the coupling membrane and electron transfer to oxygen. Clarity in this complex area is essential to prevent confusion, especially given the increasing number of interdisciplinary publications on bioenergetics related to diagnostic and clinical applications of OXPHOS analysis.