The biosynthesis of ubiquinone: Synthesis and enzymatic modification of biosynthetic precursors

The synthesis of key intermediates in the eukaryotic biosynthetic pathway of ubiquinone (Q) and the biotransformation of these materials with yeast (S.cerevisiae) mitochondria are described. The synthesis of Q aromatic precursors 2, 3, and 4 (n = 3 in all cases) relies on the palladium (0) catalyzed coupling of farnesyl tributylstannane with suitably functionalized aryl halides. Preliminary experiments show that incubation of synthetic substrate 3 with mitochondria from yeast containing the 3,4-dihydroxy-5-hexaprenylbenzoate methyltransferase gene (COQ3) and S-[methyl-³H]adenosyl-L-methionine yields radiolabeled 4.