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]
Unsaturated fatty acids and their derived fats increase the fluidity of membranes.[5]
Role in human metabolism
Fatty acid desaturase appear in all organisms: for example, bacteria, fungus, plants, animals and humans.[6] Four desaturases occur in humans: Δ9-desaturase, Δ6-desaturase, Δ5-desaturase, and Δ4-desaturase.[4]
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 (EC 1.14.19.1),[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.
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^ a bHastings N, Agaba M, Tocher DR, Leaver MJ, Dick JR, Sargent JR, Teale AJ (December 2001). "A vertebrate fatty acid desaturase with Delta 5 and Delta 6 activities". Proceedings of the National Academy of Sciences of the United States of America. 98 (25): 14304–14309. Bibcode:2001PNAS...9814304H. doi:10.1073/pnas.251516598. PMC 64677. PMID 11724940.
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^Sugiura T, Kondo S, Kishimoto S, Miyashita T, Nakane S, Kodaka T, et al. (January 2000). "Evidence that 2-arachidonoylglycerol but not N-palmitoylethanolamine or anandamide is the physiological ligand for the cannabinoid CB2 receptor. Comparison of the agonistic activities of various cannabinoid receptor ligands in HL-60 cells". The Journal of Biological Chemistry. 275 (1): 605–612. doi:10.1074/jbc.275.1.605. PMID 10617657.
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This article incorporates text from the public domain Pfam and InterPro: IPR005067