Succinate dehydrogenase is an enzyme that is involved both in the Krebs cycle (citric acid cycle) and the electron transport chain (ETC). In Krebs cycle, succinate dehydrogenase catalyzes the oxidation of succinate to fumarate and at the same time in the ETC, it transfers the electrons to FADH2 to ubiquinone (coenzyme Q). This is the only enzyme that is embedded in the inner mitochondrial membrane, linking two major energy producing metabolic processes.