A novel ubiquinone reductase activity in rat cytosol.
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.
Takahashi
T
T
Faculty of Pharmaceutical Sciences, Kobe-Gakuin University, Japan.
Shitashige
M
M
Okamoto
T
T
Kishi
T
T
Goshima
K
K
D000818:Animals; D003600:Cytosol / Q000201:enzymology*; D008099:Liver / Q000201:enzymology*; D008297:Male; D008928:Mitochondria / Q000201:enzymology; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism*; D009928:Organ Specificity; D051381:Rats; D017208:Rats, Wistar; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000378:metabolism
D014451:Ubiquinone; D016660:NAD(P)H Dehydrogenase (Quinone); C003741:ubiquinol