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Acyl-CoA dehydrogenase Both mitochondrial acyl-CoA dehydrogenases (ACAD) and peroxisomal acyl-CoA oxidases (AXO) 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. In contrast, AXO catalyzes a different oxidative half-reaction, in which the reduced FAD is reoxidized by molecular oxygen. The ACAD family includes the eukaryotic beta-oxidation enzymes, short (SCAD), medium (MCAD), long (LCAD) and very-long (VLCAD) chain acyl-CoA dehydrogenases. These enzymes all share high sequence similarity, but differ in their substrate specificities. The ACAD family also includes amino acid catabolism enzymes such as Isovaleryl-CoA dehydrogenase (IVD), short/branched chain acyl-CoA dehydrogenases(SBCAD), Isobutyryl-CoA dehydrogenase (IBDH), glutaryl-CoA deydrogenase (GCD) and Crotonobetainyl-CoA dehydrogenase. The mitochondrial ACAD's are generally homotetramers, except for VLCAD, which is a homodimer. Related enzymes include the SOS adaptive reponse proten aidB, Naphthocyclinone hydroxylase (NcnH), and and Dibenzothiophene (DBT) desulfurization enzyme C (DszC)
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