Straight-chain enoyl-CoA thioesters from C4 up to at least C16 are processed, although with decreasing catalytic rate. a (3S)-3-hydroxyacyl-CoA = a (2E)-enoyl-CoA + H2O a 4-saturated-(3S)-3-hydroxyacyl-CoA = a (3E)-enoyl-CoA + H2O Lipid metabolism; fatty acid beta-oxidation. Belongs to the enoyl-CoA hydratase/isomerase family.