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Simultaneous Measurement of Superoxide/Hydrogen Peroxide and NADH Production by Flavin-containing Mitochondrial Dehydrogenases
Published on: February 24, 2018
Ammonium-dependent hydrogen peroxide production by mitochondria
Vera G Grivennikova1, Gary Cecchini, Andrei D Vinogradov
1Department of Biochemistry, School of Biology, Moscow State University, Moscow 119992, Russian Federation.
FEBS Letters
|July 16, 2008
Summary
Mitochondria generate hydrogen peroxide (H2O2) through ammonium-sensitive enzymes in the matrix, not primarily Complex I. This finding shifts understanding of mitochondrial reactive oxygen species production.
Area of Science:
- Biochemistry
- Mitochondrial Physiology
- Cellular Respiration
Background:
- Mitochondria are key sites of cellular respiration and reactive oxygen species (ROS) production.
- Hydrogen peroxide (H2O2) is a significant ROS with roles in cell signaling and oxidative stress.
- The precise sources of mitochondrial H2O2 generation remain incompletely understood, with Complex I often implicated.
Purpose of the Study:
- To investigate the primary source of NADH-dependent hydrogen peroxide (H2O2) generation in rat heart mitochondria.
- To determine the role of Complex I versus other mitochondrial components in H2O2 production.
- To elucidate the effect of ammonium on mitochondrial H2O2 generation.
Main Methods:
- Utilized permeabilized rat heart mitochondria and coupled submitochondrial particles.
- Assessed H2O2 production using NADH as a substrate.
- Employed Complex I-specific inhibitor (NADH-OH) and varying ammonium concentrations.
- Fractionated mitochondrial matrix proteins to isolate soluble components.
Main Results:
- NADH-supported H2O2 generation in permeabilized mitochondria was only partially inhibited by the Complex I inhibitor.
- Ammonium significantly stimulated H2O2 production in permeabilized mitochondria and isolated matrix fractions (approx. 10-fold).
- Ammonium did not affect H2O2 production by Complex I in coupled submitochondrial particles.
Conclusions:
- Complex I is not the major contributor to mitochondrial superoxide (H2O2) generation.
- Specific ammonium-sensitive NADH:oxygen oxidoreductases located in the mitochondrial matrix are responsible for the majority of mitochondrial H2O2 production.
- These findings necessitate a re-evaluation of the mechanisms underlying mitochondrial ROS generation.
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