In enzymology, a (NADPH) () is an enzyme that catalyzes the chemical reaction
Thus, the three substrates of this enzyme are , NADPH, and H<sup>+</sup>, whereas its two products are acyl-CoA and NADP<sup>+</sup>.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-CH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is acyl-CoA:NADP+ trans-2-oxidoreductase. Other names in common use include NADPH-dependent trans-2-enoyl-CoA reductase, reductase, trans-enoyl coenzyme A, and trans-2-enoyl-CoA reductase (NADPH). This enzyme participates in fatty acid elongation in mitochondria and polyunsaturated fatty acid biosynthesis.