Acyl CoA dehydrogenase
![Image 1: Structure of the medium-chain acyl-CoA dehydrogenase tetramer. FAD molecules are shown in yellow. PDB code: 1egc.](/Images/godic/202412/17/Acyl_CoA_tetramer2652.jpg")
![Image 2: The overall mechanism of Acyl-CoA dehydrogenase.](/Images/godic/202412/17/AcylCoAdehydrogenase2652.png")
![Image 3: Close-up of the medium-chain acyl-CoA dehydrogenase active site. FAD is bound. The substrate will bind in the space between Glu-376 and FAD when fatty acid oxidation is initialized. PDB code: 3mdd.](/Images/godic/202412/17/Acyl_CoA_dehydrogenase_active_site2652.jpg")
Acyl-CoA dehydrogenases (ACADs) are a class of enzymes that function to catalyze the initial step in each cycle of fatty acid β-oxidation in the mitochondria of cells. Their action results in the introduction of a trans double-bond between C2 (α) and C3 (β) of the acyl-CoA thioester substrate. Flavin adenine dinucleotide (FAD) is a required co-factor in addition to the presence of an active site glutamate in order for the enzyme to function.