The first product of fatty acid catabolism is beta unsaturated Acyl-CoA. The degradation of fatty acids occurs in the mitochondrial matrix through the b-oxidation pathway. The first Acyl-CoA intermediate is formed by the dehydrogenation of fatty Acyl-CoA catalyzed by Acyl-CoA dehydrogenase, which is an FAD enzyme.
Acyl-CoA dehydrogenase is the enzyme that catalyzes fatty Acyl-CoA oxidation to give rise to a double bond between the second and third carbon atoms. These enzymes are specific to different lengths of carbon chain fatty acids. A long chain Acyl-CoA dehydrogenase is present in the inner mitochondrial membrane, while the other types are available in the mitochondrial matrix as soluble enzymes.