Able to isomerize both 3-cis and 3-trans double bonds into the 2-trans form in a range of enoyl-CoA species. Has a preference for 3-trans substrates. a (3Z)-enoyl-CoA = a 4-saturated (2E)-enoyl-CoA (3Z)-octenoyl-CoA = (2E)-octenoyl-CoA a (3E)-enoyl-CoA = a 4-saturated (2E)-enoyl-CoA (2E)-tetradecenoyl-CoA = (3Z)-tetradecenoyl-CoA (3E)-tetradecenoyl-CoA = (2E)-tetradecenoyl-CoA (3E)-octenoyl-CoA = (2E)-octenoyl-CoA (3E)-nonenoyl-CoA = (2E)-nonenoyl-CoA Lipid metabolism; fatty acid beta-oxidation. Abundant in heart, skeletal muscle and liver. Expressed in CD34(+) T-cells and CD34(+) bone marrow cells. In the C-terminal section; belongs to the enoyl-CoA hydratase/isomerase family. It is uncertain whether Met-1 or Met-3 is the initiator. Extended N-terminus. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus. Extended N-terminus. Extended N-terminus. Extended N-terminus. Extended N-terminus. Extended N-terminus.