Biner 2018 Chimia (Aarau)

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Biner O, Schick T, Ganguin AA, von Ballmoos C (2018) Towards a synthetic mitochondrion. Chimia (Aarau) 72:291-6.

Β» PMID: 29789065 Open Access

Biner O, Schick T, Ganguin AA, von Ballmoos C (2018) Chimia (Aarau)

Abstract: Our group at the University of Bern uses biochemical and biophysical techniques to unravel details of the molecular mechanism of membrane proteins. Of special interest are the large multi-subunit complexes of the universally conserved respiratory chain and the ATP synthase that are found in mitochondria and aerobic bacteria. In a bottom-up approach using purified membrane proteins and synthetic lipids, we aim to mimic the basic processes of oxidative phosphorylation. We further develop methodologies to increase the complexity of such artificial systems, paving the way for a synthetic mitochondrion. In this minireview, we summarize recent efforts of our groups and others towards a synthetic respiratory chain.

β€’ Bioblast editor: Gnaiger E

Biner 2018 Chimia (Aarau) CORRECTION.png

Hydrogen ion ambiguities in the electron transfer system

Communicated by Gnaiger E (2023-10-08) last update 2023-11-10
Electron (e-) transfer linked to hydrogen ion (hydron; H+) transfer is a fundamental concept in the field of bioenergetics, critical for understanding redox-coupled energy transformations.
Ambiguity alert H+.png
However, the current literature contains inconsistencies regarding H+ formation on the negative side of bioenergetic membranes, such as the matrix side of the mitochondrial inner membrane, when NADH is oxidized during oxidative phosphorylation (OXPHOS). Ambiguities arise when examining the oxidation of NADH by respiratory Complex I or succinate by Complex II.
Ambiguity alert e-.png
Oxidation of NADH or succinate involves a two-electron transfer of 2{H++e-} to FMN or FAD, respectively. Figures indicating a single electron e- transferred from NADH or succinate lack accuracy.
Ambiguity alert NAD.png
The oxidized NAD+ is distinguished from NAD indicating nicotinamide adenine dinucleotide independent of oxidation state.
NADH + H+ β†’ NAD+ +2{H++e-} is the oxidation half-reaction in this H+-linked electron transfer represented as 2{H++e-} (Gnaiger 2023). Putative H+ formation shown as NADH β†’ NAD+ + H+ conflicts with chemiosmotic coupling stoichiometries between H+ translocation across the coupling membrane and electron transfer to oxygen. Ensuring clarity in this complex field is imperative to tackle the apparent ambiguity crisis and prevent confusion, particularly in light of the increasing number of interdisciplinary publications on bioenergetics concerning diagnostic and clinical applications of OXPHOS analysis.


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