Involved in the final reduction of the elongation cycle of fatty acid synthesis (FAS II). Catalyzes the NADH-dependent reduction of the carbon-carbon double bond in the enoyl moiety that is covalently linked to an acyl carrier protein (ACP). a 2,3-saturated acyl-[ACP] + NAD(+) = a (2E)-enoyl-[ACP] + H(+) + NADH Resistant to triclosan. Lipid metabolism; fatty acid biosynthesis. Monomer. Belongs to the TER reductase family.