出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/03/31 04:42:04」(JST)
| Fatty acid desaturase, type 1 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | Fatty_acid_desaturase-1 | ||||||||
| Pfam | PF00487 | ||||||||
| InterPro | IPR005804 | ||||||||
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| Fatty acid desaturase, type 2 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | Fatty_acid_desaturase-2 | ||||||||
| Pfam | PF03405 | ||||||||
| InterPro | IPR005067 | ||||||||
|
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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
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.
Maintain structure and function of membranes within cells of the organisms above. This is important when temperatures changes and the membrane is under distress. The enzyme creates the double bond C-Cs which allow the membrane to become more fluid and the temperature is decreased.[1] When temperatures change, a phase transition occurs. In the case of a temperature decrease, the membrane gels and becomes solid which can result in cracks and the imbedded proteins cannot partake in conformational changes, therefore it is important to maintain membrane fluidity.[2]
Fatty acid desaturase appear in all organisms: for example, bacteria fungus plants animals and humans.[1] Four desaturases occur in humans: Δ9 desaturase, Δ6 desaturase, Δ5 desaturase, and Δ4 desaturase.
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, 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 α-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.
DEGS1; DEGS2; FADS1; FADS2; FADS3; FADS6; SCD4; SCD5
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".[3] These polyunsaturated fatty acids are important for ideal health within humans and are essential for development. By creating desaturations at the Δ6 and Δ5 positions in the carbon backbone with the addition of an elongation allows the process of linoleic acid to achidonic acid and from α-linolenic acid to eicosapentaenoic acid to partake.[3]
Δ-desaturases are represented by two distinct families which do not seem to be evolutionarily related.
Family 1 includes Stearoyl-CoA desaturase-1 (SCD) (EC 1.14.19.1).[4]
Family 2 is composed of:
Kodama et al. (1994) found that an increased amount of trienoic fatty acids allow plants to become more tolerant to cold temperatures.[7] These trienoic fatty acids are associated with plant response to cold temperatures and allows the plant to adjust. They determined that transgenic tobacco plants that contained a fatty acid desaturase gene were able to tolerate low temperatures better than wild-type plants.[7]
The yeast Saccharomyces cerevisiae has only a single Δ9 fatty acid desaturase encoded by the gene OLE1.[8]
Nakamura MT, Nara TY (2004). "Structure, function and dietary regulation of Δ6, Δ5 and Δ9 desaturases". Annual Review of Nutrition. 24 (1): 345–76. doi:10.1146/annurev.nutr.24.121803.063211. PMID 15189125.
This article incorporates text from the public domain Pfam and InterPro IPR005067
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| リンク元 | 「脱飽和酵素」「不飽和化酵素」 |
| 拡張検索 | 「stearoyl-CoA desaturase」「linoleoyl-CoA desaturase」「fatty acid desaturase」「delta-6-desaturase」 |
[★] ステアロイルCoA不飽和酵素、ステアリン酸CoA脱飽和酵素