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0  structures 2567  species 0  interactions 9036  sequences 46  architectures

Family: FA_desaturase (PF00487)

Summary: Fatty acid desaturase

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This is the Wikipedia entry entitled "Fatty acid desaturase". More...

Fatty acid desaturase Edit Wikipedia article

Fatty acid desaturase, type 1
Identifiers
Symbol Fatty_acid_desaturase-1
Pfam PF00487
InterPro IPR005804
Fatty acid desaturase, type 2
Identifiers
Symbol Fatty_acid_desaturase-2
Pfam PF03405
InterPro IPR005067

A fatty acid desaturase is an enzyme that removes two hydrogen atoms from a fatty acid, creating a carbon/carbon double bond. These desaturases are classified as

  • 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.

In the biosynthesis of essential fatty acids, an elongase alternates with different desaturases (for example, Δ6desaturase) repeatedly inserting an ethyl group, then forming a double bond.

[edit] 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:

DEGS1; DEGS2; FADS1; FADS2; FADS3; FADS6; SCD4; SCD5

[edit] Classification

Δ-desaturases are represented by two distinct families which do not seem to be evolutionary related.

Family 1 includes Stearoyl-CoA desaturase-1 (SCD) (EC 1.14.19.1).[1]

Family 2 is composed of:

  • - Bacterial fatty acid desaturases.
  • - Plant stearoyl-acyl-carrier-protein desaturase (EC 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.

[edit] References

  1. ^ 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.
  2. ^ 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. //www.ncbi.nlm.nih.gov/pmc/articles/PMC51262/.
  3. ^ 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.

This article incorporates text from the public domain Pfam and InterPro IPR005067

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

Fatty acid desaturase Provide feedback

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Literature references

  1. Lindqvist Y, Huang W, Schneider G, Shanklin J; , EMBO J 1996;15:4081-4092.: Crystal structure of delta9 stearoyl-acyl carrier protein desaturase from castor seed and its relationship to other di-iron proteins. PUBMED:8861937 EPMC:8861937


External database links

This tab holds annotation information from the InterPro database.

InterPro entry 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:

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 1.

Gene Ontology

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(127)
Full
(9036)
Representative proteomes NCBI
(8639)
Meta
(3621)
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(1025)
RP35
(1826)
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RP75
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  Seed
(127)
Full
(9036)
Representative proteomes NCBI
(8639)
Meta
(3621)
RP15
(1025)
RP35
(1826)
RP55
(2610)
RP75
(3138)
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  Seed
(127)
Full
(9036)
Representative proteomes NCBI
(8639)
Meta
(3621)
RP15
(1025)
RP35
(1826)
RP55
(2610)
RP75
(3138)
Raw Stockholm Download   Download   Download   Download   Download   Download   Download   Download  
Gzipped Download   Download   Download   Download   Download   Download   Download   Download  

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Seed source: Bateman A
Previous IDs: none
Type: Domain
Author: Finn RD, Bateman A
Number in seed: 127
Number in full: 9036
Average length of the domain: 228.30 aa
Average identity of full alignment: 15 %
Average coverage of the sequence by the domain: 66.62 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 24.9 24.9
Trusted cut-off 24.9 24.9
Noise cut-off 24.8 24.8
Model length: 257
Family (HMM) version: 19
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