Short/Branched Chain Acyl CoA Dehydrogenase is a mitochondrial enzyme that belongs to the Acyl CoA Dehydrogenase family of enzymes. Like other members of this family, the ACADSB enzyme also catalyzes the first step of beta-oxidation of fatty acids using FAD as a cofactor. However, this enzyme shows the highest affinity towards short branched chain acyl-CoA derivatives, especially 2-methylbutyryl-CoA, isobutyryl-CoA, and hexanoyl-CoA. ACADSB also catalyzes an important step in the metabolism of the amino acid isoleucine.