ECH1 is a member of the hydratase/isomerase superfamily. ECH1 demonstrates high sequence similarity to enoyl-coenzyme A（CoA) hydratases of more than a few species， mostly within a conserved domain characteristic of these proteins. ECH1 contains a C-terminal peroxisomal targeting sequence， localizes to both the peroxisome and the mitochondria. peroxisomal takes part in the auxiliary step of the fatty acid beta-oxidation pathway specifically functioning to catalyze the isomerization of 3-trans， 5-cis-dienoyl-CoA to 2-trans， 4-transdienoyl-CoA.
