Ubiquinone biosynthesis by mitochondria sonicated mitochondria and mitoplasts of rat liver

Abstract:  Ubiquinone biosynthesis by mitochondria, sonicated mitochondria, and mitoplasts of rat liver. Kang D, Fujiwara T, Takeshige K. Department of Clinical Chemistry, Fukuoka University School of Medicine. Ubiquinon e was biosynthesized when rat liver mitochondria were incubated with S-adenosyl-L-methion ine, solanesyl diphosphate, and [U-14C]p-hydroxybenz oate. The intermediates of ubiquinone biosynthesis but not ubiquinone were accumulated in mitochondria incubated without S-adenosyl-L-methion ine and the accumulated intermediates were converted to ubiquinone by the addition of the methyl group donor and an excess of cold p-hydroxybenzoate. No solaneylated compounds except nonaprenyl p-hydroxybenzoate were found in sonicated mitochondria, while the biosynthesis of ubiquinone was observed in the sonicated preparation of mitochondria in which the intermediates accumulated. The results indicate that the initial decarboxylation reaction is completely abolished and the subsequent reactions of hydroxylation and methylation are not completely inhibited by the sonication treatment and therefore the decarboxylation reaction is the next step after nonaprenylation of p-hydroxybenzoate. Mitoplasts could biosynthesize ubiquinone with activity comparable to that of intact mitochondria, suggesting that components of the outer membrane and the intermembranous space of mitochondria are not involved in ubiquinone biosynthesis. PMID: 1587800 [PubMed - indexed for MEDLINE]