PECI, also referred to as DRS1, ACBD2 or HCA88, is a protein that localizes to the peroxisomal matrix and contains one ACB (acyl-CoA-binding) domain. This protein is expressed abundantly in liver, heart and skeletal muscle. It functions to catalyze the isomerization of both 3-cis and 3-trans double bonds into the 2-trans form in a range of enoyl-CoA species, playing an important role in the b-oxidation of unsaturated fatty acids.