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Mitochondrial superoxide anion production and release into intermembrane space
Derick Han1, Fernando Antunes, Francesca Daneri
1Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of Southern California, Los Angeles, California 90033, USA.
Methods in Enzymology
|March 27, 2002
Summary
Mitochondria
Area of Science:
- Mitochondrial biochemistry
- Cellular respiration
- Oxidative stress
Background:
- Ubiquinone's location in mitochondria suggests dual roles in superoxide production.
- Superoxide (O2.-) release into mitochondrial compartments is not fully understood.
Purpose of the Study:
- To investigate the vectorial release of superoxide (O2.-) from the mitochondrial respiratory chain.
- To determine if intermembrane space superoxide contributes to cytosolic hydrogen peroxide.
Main Methods:
- Utilized mitoplasts (digitonin or hypotonic KCl treatment) as an experimental model.
- Employed membrane-impermeable spin-broadening agents to detect intermembrane space O2.-.
Main Results:
- Confirmed O2.- generation by the respiratory chain.
- Demonstrated vectorial release of O2.- into the intermembrane space.
- Indicated potential contribution of intermembrane space O2.- to cytosolic H2O2.
Conclusions:
- Both ubiquinone pools may contribute to mitochondrial superoxide production.
- Superoxide is released into the mitochondrial intermembrane space.
- Mitochondrial intermembrane space superoxide, possibly via Cu, Zn-superoxide dismutase, contributes to cytosolic hydrogen peroxide levels.