Fatty Acid Desaturases
Lipids Metabolism

Author: Gianpiero Pescarmona
Date: 16/04/2010


A Desaturase is an enzyme that removes two hydrogen atoms from an organic compound, creating a carbon/carbon double bond.

It requires NADPH and heme (iron, estrogens, Vit.B6)

Four desaturases occur in humans: Δ9 desaturase (SCD, FADS3), Δ6 desaturase (FADS2, FADS6), Δ5 desaturase (FADS1). HGNC FADS



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. Δ9 desaturase produces oleic acid by desaturating stearic acid or palmitoleic acid from palmitic acid. It exists in 2 isoforms: ACOD_HUMAN and SCD5_HUMAN

Protein Aminoacids Percentage



When relevant for the function

  • Primary structure
  • Secondary structure
  • Tertiary structure
  • Quaternary structure

Protein Aminoacids Percentage (Width 700 px)


mRNA synthesis

  • Insulin also up-regulates these three genes in the Sertoli cell, while SCD1 mRNA is down-regulated by both insulin and dexamethasone.
  • FSH. FSH seems to be a key regulator of the desaturase expression in the Sertoli cell.
    Delta5- and Delta6-desaturase, SCD1, and SCD2 are all up-regulated by FSH. A similar up-regulation of the desaturases is observed when treating Sertoli cells with (Bu)2cAMP, indicating that the desaturase up-regulation observed with FSH treatment results from
    • elevated levels of cAMP.
  • testosterone has no influence on the desaturase gene expression.
  • DEsametasone. As opposed to what is shown in liver, Delta5- and Delta6-desaturase mRNA levels in Sertoli cells are up-regulated by dexamethasone.
    Expression and regulation of delta5-desaturase, delta6-desaturase, stearoyl-coenzyme A (CoA) desaturase 1, and stearoyl-CoA desaturase 2 in rat testis. 2003

protein synthesis

Papers delta 6 desaturase estrogen

post-translational modifications


cellular localization,
biological function

Hum Mol Genet. 2006 Jun 1;15(11):1745-56. Epub 2006 May 2.

Common genetic variants of the FADS1 FADS2 gene cluster and their reconstructed haplotypes are associated with the fatty acid composition in phospholipids. 2006
Schaeffer L, Gohlke H, Müller M, Heid IM, Palmer LJ, Kompauer I, Demmelmair H, Illig T, Koletzko B, Heinrich J.

GSF-National Research Center for Environment and Health, Institute of Epidemiology, 85764 Neuherberg, Germany.

Fatty acid composition in membranes plays an important role in cellular processes and has shown to be associated with the aetiology of several complex diseases in humans. We report strong associations between variants in the human delta-5 and delta-6 desaturase genes FADS1 FADS2 and fatty acid composition in serum phospholipids. Eighteen polymorphisms located in this gene cluster were genotyped in 727 adults from Erfurt, a German centre of the European Community Respiratory Health Survey. The cluster is located at chromosome 11q12-11q13.1, a region repeatedly found to be linked with atopy and other complex diseases. Polymorphisms and statistically reconstructed haplotypes of FADS1 and the upstream region of FADS2 showed strongest associations with the level of the direct precursor of inflammatory eicosanoids, the n-6 fatty acid arachidonic acid (C20:4n-6), also strong associations with levels of the n-6 fatty acids C18:2n-6, C18:3n-6, C20:2n-6, C20:3n-6, C22:4n-6 and of the n-3 fatty acids C18:3n-3, C20:5n-3 and C22:5n-3 (P-values < 1.0 × 10(-13)). Carriers of the rare alleles of several SNPs and their respective haplotypes had a lower prevalence of allergic rhinitis and atopic eczema. No association was found for total and specific IgE(IgE) levels.



2012-09-11T12:33:41 - Annamaria Vernone

ACOD_HUMAN Acyl-CoA desaturase

Stearyl-CoA desaturase that utilizes O2 and electrons from reduced cytochrome b5 to introduce the first double bond into saturated fatty acyl-CoA substrates (PubMed:15907797, PubMed:18765284). Catalyzes the insertion of a cis double bond at the delta-9 position into fatty acyl-CoA substrates including palmitoyl-CoA and stearoyl-CoA (PubMed:15907797, PubMed:18765284). Gives rise to a mixture of 16:1 and 18:1 unsaturated fatty acids (PubMed:15610069). Plays an important role in lipid biosynthesis. Plays an important role in regulating the expression of genes that are involved in lipogenesis and in regulating mitochondrial fatty acid oxidation (By similarity). Plays an important role in body energy homeostasis (By similarity). Contributes to the biosynthesis of membrane phospholipids, cholesterol esters and triglycerides

Catalytic activity

Stearoyl-CoA + 2 ferrocytochrome b5 + O2 + 2 H+ = oleoyl-CoA + 2 ferricytochrome b5 + 2 H2O.

ACOD_HUMAN has an high glu/gln ratio, greater than 2.5 but low single values for glu and gln.
In the study Low-temperature-induced desaturation of fatty acids and expression of desaturase genes in the cyanobacterium Synechococcus sp. PCC 7002, we cam see that the effect of hypothermia is a reduction in the extracellular glutamate level.


High physiological omega-3 Fatty Acid supplementation affects muscle Fatty Acid composition and glucose and insulin homeostasis in obese adolescents

AddThis Social Bookmark Button