5-demethylubiquinone-9-methyltransferase from rat liver mitochondria. Characterization, localization, and solubilization.

摘要: Abstract The methyltransferase responsible for the conversion of 5-demethylubiquinone-9 to ubiquinone-9 in rat liver mitochondria has been shown be localized inner membrane mitochondria. NADH was required generate hydroquinone, which immediate substrate methylation. Km estimated range 60 80 nM and S-adenosylmethionine found 22 micronM. methyl-transferase solubilized by Triton X-100, a procedure inactivated reductase. Dithionite partially substitute both membranous soluble systems. Inhibitors catechol-O-methyltransferase were not effective inhibitors 5-demethylubiquinone-9-methyltransferase. In addition, 5-demethylubiquinone-9-methyltransferase have reciprocal subcellular localizations. It is likely that hydrophobic side chain ubiquinone, added p-hydroxybenzoate first biosynthetic step, attachment lipid bilayer. This permits subsequent metabolism ring system membrane-bound enzymes, including final methylation form ubiquinone-9.