Rose 2019 Adis

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Publications in the MiPMap
Rose S, Bennuri SC (2019) Mitochondrial metabolism. In: Frye R, Berk M (eds) The therapeutic use of N-acetylcysteine (NAC) in medicine. Adis, Singapore.

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Rose S, Bennuri SC (2019) Adis, Singapore

Abstract: Best known for their role in generating adenosine triphosphate (ATP) through oxidative phosphorylation, mitochondria are responsible for a wide variety of vital cellular processes including apoptosis, maintenance of calcium homeostasis, redox signaling, steroid synthesis, and lipid metabolism. The mitochondria are dynamic organelles, responding to changing cellular physiology, nutrient availability, and energy demands by changing in function as well as shape, size, distribution, and number. Given the many important roles of the mitochondria for normal cellular function, it is not surprising that mitochondrial dysfunction is involved in a wide variety of diseases and medical disorders. Despite several mechanisms to combat the leakage of electrons that accompanies electron transfer during the process of oxidative phosphorylation, mitochondria are the primary producers of reactive oxygen species (ROS) in most cell types. Given the importance of mitochondria in health and disease, the effects of the antioxidant and glutathione precursor, N-acetylcysteine (NAC), on mitochondrial function have been examined in many studies of a wide variety of medical conditions. The purpose of this review is to conduct a systematic review of the literature on the effects of NAC on mitochondrial metabolism.

β€’ Bioblast editor: Gnaiger E

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Correction: FADH2 and Complex II

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FADH2 is shown as the substrate feeding electrons into Complex II (CII). This is wrong and requires correction - for details see Gnaiger (2024).
Gnaiger E (2024) Complex II ambiguities ― FADH2 in the electron transfer system. J Biol Chem 300:105470. - Β»Bioblast linkΒ«

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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