Stearoyl CoA 9 desaturase

In enzymology, a stearoyl-CoA 9-desaturase (EC 1.14.19.1) is an enzyme used to produce the monounsaturated fatty acid oleic acid from the saturated fatty acid stearic acid. It catalyzes the chemical reaction

stearoyl-CoA + 2 ferrocytochrome b₅ + O₂ + 2 H⁺ ⇌ oleoyl-CoA + 2 ferricytochrome b₅ + 2 H₂O

The 4 substrates of this enzyme are stearoyl-CoA, ferrocytochrome b5, O₂, and H⁺, whereas its 3 products are oleoyl-CoA, ferricytochrome b5, and H₂O.

This enzyme belongs to the family of oxidoreductases, specifically those acting on paired donors, with O₂ as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O₂ 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.