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Updated: Jul 25, 2026

Simultaneous Measurement of Superoxide/Hydrogen Peroxide and NADH Production by Flavin-containing Mitochondrial Dehydrogenases
Published on: February 24, 2018
A novel ubiquinone reductase activity in rat cytosol
T Takahashi1, M Shitashige, T Okamoto
1Faculty of Pharmaceutical Sciences, Kobe-Gakuin University, Japan.
Abstract:
Ubiquinone (UQ) reductase activity which reduces UQ to ubiquinol (UQH2) in rat tissues was roughly proportional to the UQH2/total UQ ratio in respective tissues. The highest activity was found in the liver, showing the highest UQH2/total UQ ratio. A greater part of liver UQ reductase activity was located in the cytosol. Within a week, the liver UQ reductase activity decreased by 80% even at -20 degrees C. The DT-diaphorase activity was stable. UQ reductase required NADPH as the hydrogen donor and was not inhibited by a less than 1 microM concentration of dicoumarol. There was no stimulation of UQ reductase in the presence of bovine serum albumin nor in Triton X-100. Yet, both stimulated DT-diaphorase. As a result, UQ reductase appeared to be a novel NADPH-UQ oxidoreductase and responsible for the UQ redox state in liver.
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