The SDH (succinate dehydrogenase) complex, embedded in the inner mitochondrial membrane, catalyzes the reversible reduction of fumarate to succinate, coupled to the oxidation of SDH-associated FADH2 to FADH. No chicken enzyme capable of catalyzing this reaction has been characterized, although open reading frames capable of encoding three of the four proteins predicted from characterization of authentic human mitochondrial succinate dehydrogenase has been identified computationally in the ENSEMBL chicken gene set or in large-scale screens of cDNA clones. This reaction is inferred from its human counterpart.