Linoleoyl-CoA desaturase

Linoleoyl-CoA desaturase (also Delta 6 desaturase, EC 1.14.19.3) is an enzyme that converts between types of fatty acids, which are essential nutrients in the human body. The enzyme mainly catalyzes the chemical reaction

linoleoyl-CoA + AH₂ + O₂ ${\displaystyle \rightleftharpoons }$ gamma-linolenoyl-CoA + A + 2 H₂O

The three substrates of this enzyme are linoleoyl-CoA, an electron acceptor AH₂, and O₂, whereas its three products are gamma-linolenoyl-CoA, the reduction product A, 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 linoleoyl-CoA,hydrogen-donor:oxygen oxidoreductase. Other names in common use include acyl-CoA 6-desaturase, Delta6-desaturase (D6D or Δ-6-desaturase), Delta6-fatty acyl-CoA desaturase, Delta6-acyl CoA desaturase, fatty acid Delta6-desaturase, fatty acid 6-desaturase, linoleate desaturase, linoleic desaturase, linoleic acid desaturase, linoleoyl CoA desaturase, linoleoyl-coenzyme A desaturase, and long-chain fatty acid Delta6-desaturase. This enzyme participates in linoleic acid metabolism. It employs one cofactor, iron.

The enzyme is molecularly identical across all living things. It is present in animals, plants, fungi, and cyanobacteria.

D6D is one of the three fatty acid desaturases present in humans along with Δ-5 and Δ-9, named so because it was thought to desaturate bond between carbons 6 and 7, counting from carboxyl group (with the carboxyl group carbon numbered one). The number 6 in the name of the enzyme has nothing to do with omega-6 fatty acids. In humans, D6D is encoded by the FADS2 gene.