In enzymology, a carbonyl reductase (NADPH) () is an enzyme that catalyzes the chemical reaction
R-CO-R' + NADPH + H<sup>+</sup> :R-CHOH-R' + NADP<sup>+</sup>
Thus, the two products of this enzyme are R-CHOH-R' and NADP<sup>+</sup>, whereas its 3 substrates are R-CO-R', NADPH, and H<sup>+</sup>.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD<sup>+</sup> or NADP<sup>+</sup> as acceptor. The systematic name of this enzyme class is secondary-alcohol:NADP<sup>+</sup> oxidoreductase. Other names in common use include aldehyde reductase 1, prostaglandin 9-ketoreductase, xenobiotic ketone reductase, NADPH-dependent carbonyl reductase, ALR3, carbonyl reductase, nonspecific NADPH-dependent carbonyl reductase, aldehyde reductase 1, and carbonyl reductase (NADPH). This enzyme participates in arachidonic acid metabolism, and has recently been shown to catabolize S-Nitrosoglutathione, as a means to degrade NO in an NADPH-dependent manner.
As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes , , , and .