Delta - indicating that the double bond is created at a fixed position from the
carboxyl end of a
fatty acid chain. For example,
Δ9-desaturase creates a double bond between the ninth and tenth carbon atom from the carboxyl end.
Omega - indicating the double bond is created at a fixed position from the
methyl end of a fatty acid chain. For instance, ω3 desaturase creates a double bond between the third and fourth carbon atom from the methyl end. In other words, it creates an
omega-3 fatty acid.
Desaturases have diiron
active sites reminiscent of
methane monooxygenase. These enzymes are O2-dependent, consistent with their function as either hydroxylation or oxidative dehydrogenation.[3]
Δ9-desaturase, also known as
stearoyl-CoA desaturase-1, is used to synthesize
oleic acid, a monounsaturated, ubiquitous component of all cells in the human body, and the major fatty acid in
mammalianadiposetriglycerides, and also used for
phospholipid and
cholesteryl ester synthesis.[4] Δ9-desaturase produces oleic acid (C18H34O2; 18:1-n9) by desaturating
stearic acid (SA: C18H36O2; 18:0), a saturated fatty acid either synthesized in the body from
palmitic acid (PA: C16H32O2; 16:0) or ingested directly.
Vertebrates are unable to synthesize polyunsaturated fatty acids because they do not have the necessary fatty acid desaturases to "convert oleic acid (18:1n-9) into linoleic acid (18:2n-6) and α-linolenic acid (18:3n-3)".[7] Linoleic acid (LA) and α-linolenic acid (ALA) are essential for human health and development, and should therefore be consumed by diets, like 15 ml of
hemp seed oil, or/and 33 gram of
hemp seed protein a day,[13] can provide all the
protein, essential fatty acids, and
dietary fiber necessary for human survival for one day,[14] as their absence has been found responsible for the development of a wide range of diseases such as
metabolic disorders,[15]cardiovascular disorders,
inflammatory processes,
viral infections, certain types of
cancer and
autoimmune disorders.[16]
Plant stearoyl-
acyl-carrier-protein desaturase (
EC1.14.19.1),[18] an enzyme that 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,[19] an enzyme that can introduce a second cis double bond at the delta-12 position of fatty acid bound to membrane glycerolipids. This enzyme 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.
^Jiao J, Zhang Y (May 2013). "Transgenic biosynthesis of polyunsaturated fatty acids: a sustainable biochemical engineering approach for making essential fatty acids in plants and animals". Chemical Reviews. 113 (5): 3799–3814.
doi:
10.1021/cr300007p.
PMID23421688.
^Los DA, Murata N (October 1998). "Structure and expression of fatty acid desaturases". Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism. 1394 (1): 3–15.
doi:
10.1016/S0005-2760(98)00091-5.
PMID9767077.
^Guil-Guerrero JL, Rincón-Cervera MÁ, Venegas-Venegas E (2010). "Gamma-linolenic and stearidonic acids: Purification and upgrading of C18-PUFA oils". European Journal of Lipid Science and Technology. 112 (10): 1068–1081.
doi:
10.1002/ejlt.200900294.
ISSN1438-7697.