Stearoyl-CoA 9-desaturase
In enzymology, a stearoyl-CoA 9-desaturase () is an enzyme used to produce the monounsaturated fatty acid oleic acid from the saturated fatty acid stearic acid. It catalyzes the chemical reaction The 4 substrates of this enzyme are stearoyl-CoA, ferrocytochrome b5, O, and H, whereas its 3 products are oleoyl-CoA, ferricytochrome b5, and HO. This enzyme belongs to the family of oxidoreductases, specifically those acting on paired donors, with O as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O with oxidation of a pair of donors  resulting in the reduction of O to two molecules of water. The systematic name of this enzyme class is stearoyl-CoA,ferrocytochrome-b5:oxygen oxidoreductase (9,10-dehydrogenating). Other names in common use include Delta9-desaturase, acyl-CoA desaturase, fatty acid desaturase, and stearoyl-CoA, hydrogen-donor:oxygen oxidoreductase. This enzyme participates in polyunsaturated fatty acid biosynthesis and ppar signaling pathway. It employs one cofactor, iron.