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Related Experiment Video

Updated: May 27, 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

Nitrogen dioxide oxidizes mitochondrial cytochrome c.

Rebecca S Silkstone¹, Maria G Mason, Peter Nicholls

¹Department of Biological Sciences, University of Essex, Colchester, Essex, UK.

Free Radical Biology & Medicine

|November 22, 2011

Summary

This summary is machine-generated.

Nitric oxide (NO) does not directly oxidize mitochondrial cytochrome c. Instead, nitrogen dioxide (NO2•), formed during NO

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Oxygen-Independent Assays to Measure Mitochondrial Function in Mammals

Oxygen-Independent Assays to Measure Mitochondrial Function in Mammals

Published on: May 19, 2023

Area of Science:

Biochemistry
Cellular Respiration
Oxidative Stress

Background:

Previous studies suggested nitric oxide (NO) directly oxidizes mitochondrial cytochrome c.
Re-evaluation of redox potentials indicated this reaction is thermodynamically unfavorable.

Purpose of the Study:

To investigate the mechanism of nitric oxide-mediated cytochrome c oxidation.
To identify the reactive species responsible for cytochrome c oxidation by NO.

Main Methods:

Studying the oxygen-concentration dependence of NO-induced cytochrome c oxidation.
Employing kinetic modeling of NO autoxidation.
Utilizing scavengers like urate and ferrocyanide to probe the reaction mechanism.

Main Results:

Cytochrome c oxidation by NO is oxygen-dependent and non-stoichiometric.
The primary oxidant is identified as nitrogen dioxide (NO2•), a product of NO aerobic decay.
A kinetic model accurately predicted cytochrome c oxidation rates with NO2•.
Scavengers confirmed the role of NO2• by altering oxidation extents.

Conclusions:

The direct oxidation of cytochrome c by NO is unlikely.
Nitrogen dioxide (NO2•) is the principal species mediating cytochrome c oxidation in aerobic conditions.
The findings refute previous hypotheses involving nitroxyl ions or peroxynitrite in this reaction.