Key enzyme of fatty acid beta-oxidation (Probable). Able to isomerize both 3-cis (3Z) and 3-trans (3E) double bonds into the 2-trans (2E) form in a range of enoyl-CoA species, with a preference for (3Z)-enoyl-CoAs over (3E)-enoyl-CoAs  (By similarity). The catalytic efficiency of this enzyme is not affected by the fatty acyl chain length (By similarity).
Subcellular locations: Mitochondrion matrix
Expressed in liver (at protein level).