Stearoyl-CoA 9-desaturase

[5] The complexed enzyme adds a single double bond between the C9 and C10 of long-chain acyl-CoAs from de-novo synthesis.

[1] 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.

Stearoyl-CoA desaturase (SCD; EC 1.14.19.1) is an iron-containing enzyme that catalyzes a rate-limiting step in the synthesis of unsaturated fatty acids.

[9] One of the unanswered questions is that SCD remains a highly regulated enzyme, even though oleate is readily available, as it is an abundant monounsaturated fatty acid in dietary fat.

It catalyzes the chemical reaction 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.

Monounsaturated fatty acids, the products of SCD-1 catalyzed reactions, can serve as substrates for the synthesis of various kinds of lipids, including phospholipids, triglycerides, and can also be used as mediators in signal transduction and differentiation.

[19] It is believed that tumor cells obtain most part of their requirement for fatty acids by de novo synthesis.

SCD-1 knockout mice did not increase de novo lipogenesis but created an abundance of cholesterol esters.

[27] One proposed mechanism is that an increase in cell membrane fluidity, consisting largely of lipid, activates the insulin receptor.