Putative acyl-CoA dehydrogenase (ACAD). Mitochondrial acyl-CoA dehydrogenases (ACAD) catalyze the alpha,beta dehydrogenation of the corresponding trans-enoyl-CoA by FAD, which becomes reduced. The reduced form of ACAD is reoxidized in the oxidative half-reaction by electron-transferring flavoprotein (ETF), from which the electrons are transferred to the mitochondrial respiratory chain coupled with ATP synthesis. The ACD family includes the eukaryotic beta-oxidation, as well as amino acid catabolism enzymes. These enzymes share high sequence similarity, but differ in their substrate specificities. The mitochondrial ACD's are generally homotetramers and have an active site glutamate at a conserved position.