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Related Experiment Video

Updated: May 2, 2026

Simultaneous Measurement of Superoxide/Hydrogen Peroxide and NADH Production by Flavin-containing Mitochondrial Dehydrogenases

Simultaneous Measurement of Superoxide/Hydrogen Peroxide and NADH Production by Flavin-containing Mitochondrial Dehydrogenases

Published on: February 24, 2018

Superoxide generation by complex III: from mechanistic rationales to functional consequences.

Lea Bleier¹, Stefan Dröse

¹Molecular Bioenergetics Group, Medical School, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany.

Biochimica Et Biophysica Acta

|December 28, 2012

Summary

The mitochondrial cytochrome bc1 complex (complex III) is a major source of superoxide and reactive oxygen species (ROS). These ROS have signaling roles in cellular processes like hypoxia adaptation, beyond links to aging and disease.

Keywords:

Complex III Cytochrome bc(1) complex H(2)O(2)Mitochondria O(2)(−)Q Q(i) site/center N Q(o) site/center P Q(−)/SQ QH(2)ROS Reactive oxygen species Redox signaling SMPs Superoxide hydrogen peroxide reactive oxygen species semiquinone submitochondrial particles superoxide ubiquinol ubiquinol oxidation site ubiquinone ubiquinone reduction site

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Area of Science:

Biochemistry
Cellular Biology
Mitochondrial Function

Background:

Mitochondrial respiratory chain complex III (cytochrome bc1 complex) is a primary source of superoxide and reactive oxygen species (ROS).
Mitochondrial ROS are implicated in aging, oxidative stress, and neurodegenerative diseases.
ROS generated at complex III's ubiquinol oxidation site (Qo site) may function as signaling molecules, particularly in hypoxia adaptation.

Purpose of the Study:

To review the mechanistic studies of superoxide production in complex III.
To connect mechanistic insights with cellular signaling functions of complex III-derived ROS.
To highlight factors influencing superoxide generation by complex III.

Main Methods:

Review of kinetic studies using mutated yeast and bacterial cytochrome bc1 complexes.
Analysis of literature on complex III ROS in cellular signal transduction.
Synthesis of data from mechanistic and physiological investigations.

Main Results:

Complex III is a significant producer of mitochondrial superoxide and ROS.
Superoxide production is linked to electron bifurcation during ubiquinol oxidation.
Complex III ROS play physiological roles in signaling, such as during hypoxia response.

Conclusions:

Understanding the mechanism of ROS production in complex III is crucial.
Complex III ROS are key signaling molecules in cellular adaptation.
Bridging mechanistic and physiological studies will advance knowledge of ROS function.