Coenzyme Q (CoQ or Ubiquinone)

CoQ is a component of the inner mitochondrial membrane involved in the process of electron transport. It draws electrons into the respiratory chain, not only from NADH but also from succinate, as shown in Figure 15.3.

Because CoQ is subsequently oxidized by cytochromes, it can be seen as a collection point, gathering electrons from several flavoprotein dehydrogenases and passing them along to cytochromes for ultimate transport to O 2. Further, since CoQ oxido-reduction proceeds one electron at a time through a semiquinone intermediate, CoQ provides an interface between two-electron carriers and the one-electron cytochromes.

Chorismic Acid is a metabolic precursor in biosynthesis of CoQ.

See also: Figure 21.13, Figure 21.14, p-Hydroxybenzoic Acid