InterPro domain: IPR005804

Fatty acid desaturases are enzymes that catalyse the insertion of a double bond at the delta position of fatty acids. There seem to be two distinct families of fatty acid desaturases which do not seem to be evolutionary related.

Family 1 is composed of:

• Stearoyl-CoA desaturase (SCD) ( 1.14.19.1 ) [ 1 ].

Family 2 is composed of:

• Bacterial fatty acid desaturases.
• Plant stearoyl-acyl-carrier-protein desaturase ( 1.14.19.1 ) [ 2 ], this enzyme catalyzes the introduction of a double bond at the delta(9) position of steraoyl-ACP to produce oleoyl-ACP. This enzyme is responsible for the conversion of saturated fatty acids to unsaturated fatty acids in the synthesis of vegetable oils.
• Cyanobacterial DesA [ 3 ], an enzyme that can introduce a second cis double bond at the delta(12) position of fatty acid bound to membranes glycerolipids. DesA is involved in chilling tolerance; the phase transition temperature of lipids of cellular membranes being dependent on the degree of unsaturation of fatty acids of the membrane lipids.

1. Differentiation-induced gene expression in 3T3-L1 preadipocytes. A second differentially expressed gene encoding stearoyl-CoA desaturase. J. Biol. Chem. 264, 14755-61
2. Stearoyl-acyl-carrier-protein desaturase from higher plants is structurally unrelated to the animal and fungal homologs. Proc. Natl. Acad. Sci. U.S.A. 88, 2510-4
3. Enhancement of chilling tolerance of a cyanobacterium by genetic manipulation of fatty acid desaturation. Nature 347, 200-3