Studies on reduced and oxidized coenzyme Q (ubiquinones). II. The determination of oxidation-reduction levels of coenzyme Q in mitochondria,microsomes and plasma by high-performance liquid chromatography |
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Authors: | Masahiro Takada Satoru Ikenoya Teruaki Yuzuriha Kouichi Katayama |
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Affiliation: | 1. Department of Drug Metabolism, Research and Development Division, Eisai Co., Ltd., Koishikawa, Bunkyo-ku, Tokyo Japan;2. Department of Analytical Chemistry, Research and Development Division, Eisai Co., Ltd., Koishikawa, Bunkyo-ku, Tokyo Japan |
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Abstract: | Reduced and oxidized coenzyme Q10 (Q10H2 and Q10) in guinea-pig liver mitochondria were rapidly extracted and determined by high-performance liquid chromatography (HPLC). The percentages of Q10H2 as compared to the total (sum of Q10 and Q10H2) were increased by the addition of respiratory substrates such as succinate, malate and β-hydroxybutyrate (State 4). The levels of Q10H2 in State 4 were increased more extensively with electron-transport inhibitors such as KCN, NaN3 and antimycin A. These results indicate that the method for determining Q10H2 and Q10 by HPLC is quite useful for investigation of the physiological function of coenzyme Q in mitochondria and other organelles. The reduced and oxidized coenzyme Q levels of rat liver mitochondria, which contain both coenzyme Q9 and coenzyme Q10, were measured simultaneously. The results suggest that coenzymes Q9 and Q10 play a similar role as an electron carriers. The liver microsomes of guinea-pig contained approx. 133 nmol total coenzyme Q10 per g protein. The Q10H2 levels of microsomes were increased from 46.5 to 67.5 and 64.8% with NADH and NADPH, respectively. The plasma levels of total coenzyme Q were 0.92 μg/ml for man, 0.35 μg/ml for guinea-pig and 0.27 μg/ml for rat. The reduced coenzyme Q were also present in those plasma samples. The levels of reduced coenzyme Q were 51.1, 48.9 and 65.3%, respectively. |
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Keywords: | Coenzyme Q Ubiquinone Redox level Oxygen consumption HPLC Q the general term for oxidized coenzyme Q homologues the general term for reduced coenzyme Q homologues HPLC high-performance liquid chromatography |
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