Summary: Fatty acid desaturase
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Fatty acid desaturase Edit Wikipedia article
|Fatty acid desaturase, type 1|
|Fatty acid desaturase, type 2|
- delta - indicating that the double bond is created at a fixed position from the carboxyl group of a fatty acid (for example, Δ9desaturase creates a double bond at the 9th position from the carboxyl end).
- omega (e.g. ω3desaturase) - indicating the double bond is created between the third and fourth carbon from the methyl end of the fatty acid.
Role in human metabolism
Four desaturases occur in humans: Δ9desaturase, Δ6desaturase, Δ5 desaturase, and Δ4 desaturase.
Δ9desaturase, also known as stearoyl-CoA desaturase-1, is used to synthesize oleic acid, a monounsaturated, ubiquitous component of all cells in the human body. Δ9desaturase produces oleic acid by desaturating stearic acid, a saturated fatty acid either synthesized in the body from palmitic acid or ingested directly.
Δ6 and Δ5 desaturases are required for the synthesis of highly unsaturated fatty acids such as eicosopentaenoic and docosahexaenoic acids (synthesized from a-linolenic acid), and arachidonic acid (synthesized from linoleic acid). This is a multi-stage process requiring successive actions by elongase and desaturase enzymes. The genes coding for Δ6 and Δ5 desaturase production have been located on human chromosome 11.
- Human fatty acid desaturases:
Δ-desaturases are represented by two distinct families which do not seem to be evolutionarily related.
Family 2 is composed of:
- - Bacterial fatty acid desaturases.
- - Plant stearoyl-acyl-carrier-protein desaturase (EC 18.104.22.168), 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, 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.
- Lane MD, Ntambi JM, Kaestner KH, Kelly Jr TJ (1989). "Differentiation-induced gene expression in 3T3-L1 preadipocytes. A second differentially expressed gene encoding stearoyl-CoA desaturase". J. Biol. Chem. 264 (25): 14755–14761. PMID 2570068.
- Shanklin J, Somerville C (1991). "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 (6): 2510–2514. doi:10.1073/pnas.88.6.2510. PMC 51262. PMID 2006187.
- Wada H, Gombos Z, Murata N (1990). "Enhancement of chilling tolerance of a cyanobacterium by genetic manipulation of fatty acid desaturation". Nature 347 (6289): 200–203. doi:10.1038/347200a0. PMID 2118597.
Nakamura MT, Nara TY (2004). "Structure, function and dietary regulation of Δ6, Δ5 and Δ9 desaturases". Annual Review of Nutrition 24 (24): 345–76. doi:10.1146/annurev.nutr.24.121803.063211. PMID 15189125.
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No Pfam abstract.
Internal database links
|SCOOP:||DUF892 AurF Ferritin_2|
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR005067
Fatty acid desaturases are enzymes that catalyze 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:
Family 2 is composed of:
- - Bacterial fatty acid desaturases.
- - Plant stearoyl-acyl-carrier-protein desaturase (EC) [PUBMED:2006187], 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 [PUBMED:2118597], 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.
This entry contains fatty acid desaturases belonging to Family 2.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Molecular function||acyl-[acyl-carrier-protein] desaturase activity (GO:0045300)|
|Biological process||fatty acid metabolic process (GO:0006631)|
|oxidation-reduction process (GO:0055114)|
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The members of this clan all share a distinctive four helical bundle. The four helices are arranged antiparallel with a left-handed twist. This helical bundle is distinguished from others by the long connection between the second and third helices. Some of the members contain a Fe or Mn dimer at the centre of the helical bundle. The ferritin fold was first described by Murzin AG and Chothia C, Cur Opin Struc Biol 1992, 2:895-903.
The clan contains the following 21 members:AurF Coat_F COQ7 DUF2202 DUF2383 DUF305 DUF3066 DUF4142 DUF4439 DUF892 FA_desaturase_2 Ferritin Ferritin-like Ferritin_2 MiaE MiaE_2 Mn_catalase PaaA_PaaC Phenol_Hydrox Ribonuc_red_sm Rubrerythrin
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|Seed source:||Bateman A|
|Number in seed:||56|
|Number in full:||576|
|Average length of the domain:||267.10 aa|
|Average identity of full alignment:||37 %|
|Average coverage of the sequence by the domain:||85.23 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 11927849 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||11|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the FA_desaturase_2 domain has been found. There are 37 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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