Click on image to view larger version.
Fig. 3. Sites for semiquinone formation in the redox complexes of mitochondria. Complex I, II and III generate semiquinone which takes part in normal electron transfer. If semiquinone accumulates because of inhibitors, excess substrate or excess proton accumulation, the semiquinone can be autooxidized to produce superoxide [26]. Semiquinone formation in fatty acid oxidation (FA) would probably be associated with the electron transfer flavoprotein (ETFP) coenzyme Q oxidoreductase ETFQR [70]. Glycerol-3-phosphate dehydrogenase also reacts with coenzyme Q (not shown [71]).
